diff --git a/enc/ascii.c b/enc/ascii.c
index ae7db97f25ed79..4ba93f4febdb21 100644
--- a/enc/ascii.c
+++ b/enc/ascii.c
@@ -54,7 +54,11 @@ OnigEncodingDefine(ascii, ASCII) = {
   onigenc_not_support_get_ctype_code_range,
   onigenc_single_byte_left_adjust_char_head,
   onigenc_always_true_is_allowed_reverse_match,
+#ifdef USE_CASE_MAP_API
   onigenc_single_byte_ascii_only_case_map,
+#else
+  NULL,
+#endif
   ENCINDEX_ASCII_8BIT,
   ONIGENC_FLAG_NONE,
 };
diff --git a/enc/big5.c b/enc/big5.c
index ab4fb69819b60e..e141ebdbe36988 100644
--- a/enc/big5.c
+++ b/enc/big5.c
@@ -300,7 +300,11 @@ OnigEncodingDefine(big5, BIG5) = {
   onigenc_not_support_get_ctype_code_range,
   big5_left_adjust_char_head,
   big5_is_allowed_reverse_match,
+#ifdef USE_CASE_MAP_API
   onigenc_ascii_only_case_map,
+#else
+  NULL,
+#endif
   0,
   ONIGENC_FLAG_NONE,
 };
@@ -335,7 +339,11 @@ OnigEncodingDefine(big5_hkscs, BIG5_HKSCS) = {
   onigenc_not_support_get_ctype_code_range,
   big5_left_adjust_char_head,
   big5_is_allowed_reverse_match,
+#ifdef USE_CASE_MAP_API
   onigenc_ascii_only_case_map,
+#else
+  NULL,
+#endif
   0,
   ONIGENC_FLAG_NONE,
 };
@@ -370,7 +378,11 @@ OnigEncodingDefine(big5_uao, BIG5_UAO) = {
   onigenc_not_support_get_ctype_code_range,
   big5_left_adjust_char_head,
   big5_is_allowed_reverse_match,
+#ifdef USE_CASE_MAP_API
   onigenc_ascii_only_case_map,
+#else
+  NULL,
+#endif
   0,
   ONIGENC_FLAG_NONE,
 };
diff --git a/enc/cp949.c b/enc/cp949.c
index 1600d0cd5bee29..77e961a7cdf3d0 100644
--- a/enc/cp949.c
+++ b/enc/cp949.c
@@ -211,7 +211,11 @@ OnigEncodingDefine(cp949, CP949) = {
   onigenc_not_support_get_ctype_code_range,
   cp949_left_adjust_char_head,
   cp949_is_allowed_reverse_match,
+#ifdef USE_CASE_MAP_API
   onigenc_ascii_only_case_map,
+#else
+  NULL,
+#endif
   0,
   ONIGENC_FLAG_NONE,
 };
diff --git a/enc/emacs_mule.c b/enc/emacs_mule.c
index f92eb183cf788d..abd986a1878e0b 100644
--- a/enc/emacs_mule.c
+++ b/enc/emacs_mule.c
@@ -334,7 +334,11 @@ OnigEncodingDefine(emacs_mule, Emacs_Mule) = {
   onigenc_not_support_get_ctype_code_range,
   left_adjust_char_head,
   onigenc_always_true_is_allowed_reverse_match,
+#ifdef USE_CASE_MAP_API
   onigenc_ascii_only_case_map,
+#else
+  NULL,
+#endif
   0,
   ONIGENC_FLAG_NONE,
 };
diff --git a/enc/euc_jp.c b/enc/euc_jp.c
index d283bf4ebb1208..678d0116682bee 100644
--- a/enc/euc_jp.c
+++ b/enc/euc_jp.c
@@ -576,7 +576,11 @@ OnigEncodingDefine(euc_jp, EUC_JP) = {
   get_ctype_code_range,
   left_adjust_char_head,
   is_allowed_reverse_match,
+#ifdef USE_CASE_MAP_API
   onigenc_ascii_only_case_map,
+#else
+  NULL,
+#endif
   0,
   ONIGENC_FLAG_NONE,
 };
diff --git a/enc/euc_kr.c b/enc/euc_kr.c
index 21d6ab4e1c10b9..4079a0ece05b20 100644
--- a/enc/euc_kr.c
+++ b/enc/euc_kr.c
@@ -188,7 +188,11 @@ OnigEncodingDefine(euc_kr, EUC_KR) = {
   onigenc_not_support_get_ctype_code_range,
   euckr_left_adjust_char_head,
   euckr_is_allowed_reverse_match,
+#ifdef USE_CASE_MAP_API
   onigenc_ascii_only_case_map,
+#else
+  NULL,
+#endif
   0,
   ONIGENC_FLAG_NONE,
 };
@@ -213,7 +217,11 @@ OnigEncodingDefine(euc_cn, EUC_CN) = {
   onigenc_not_support_get_ctype_code_range,
   euckr_left_adjust_char_head,
   euckr_is_allowed_reverse_match,
+#ifdef USE_CASE_MAP_API
   onigenc_ascii_only_case_map,
+#else
+  NULL,
+#endif
   0,
   ONIGENC_FLAG_NONE,
 };
diff --git a/enc/euc_tw.c b/enc/euc_tw.c
index 1c5659cb1d0895..722e29a9dac70e 100644
--- a/enc/euc_tw.c
+++ b/enc/euc_tw.c
@@ -221,7 +221,11 @@ OnigEncodingDefine(euc_tw, EUC_TW) = {
   onigenc_not_support_get_ctype_code_range,
   euctw_left_adjust_char_head,
   euctw_is_allowed_reverse_match,
+#ifdef USE_CASE_MAP_API
   onigenc_ascii_only_case_map,
+#else
+  NULL,
+#endif
   0,
   ONIGENC_FLAG_NONE,
 };
diff --git a/enc/gb18030.c b/enc/gb18030.c
index 63d2e633ecb16e..316737db11463d 100644
--- a/enc/gb18030.c
+++ b/enc/gb18030.c
@@ -597,7 +597,11 @@ OnigEncodingDefine(gb18030, GB18030) = {
   onigenc_not_support_get_ctype_code_range,
   gb18030_left_adjust_char_head,
   gb18030_is_allowed_reverse_match,
+#ifdef USE_CASE_MAP_API
   onigenc_ascii_only_case_map,
+#else
+  NULL,
+#endif
   0,
   ONIGENC_FLAG_NONE,
 };
diff --git a/enc/gbk.c b/enc/gbk.c
index 31032553bf58ed..3df4e4b6d6a6a9 100644
--- a/enc/gbk.c
+++ b/enc/gbk.c
@@ -211,7 +211,11 @@ OnigEncodingDefine(gbk, GBK) = {
   onigenc_not_support_get_ctype_code_range,
   gbk_left_adjust_char_head,
   gbk_is_allowed_reverse_match,
+#ifdef USE_CASE_MAP_API
   onigenc_ascii_only_case_map,
+#else
+  NULL,
+#endif
   0,
   ONIGENC_FLAG_NONE,
 };
diff --git a/enc/iso_8859_1.c b/enc/iso_8859_1.c
index 7af0888c3edced..78ea1fba600582 100644
--- a/enc/iso_8859_1.c
+++ b/enc/iso_8859_1.c
@@ -255,6 +255,7 @@ is_code_ctype(OnigCodePoint code, unsigned int ctype, OnigEncoding enc ARG_UNUSE
     return FALSE;
 }
 
+#ifdef USE_CASE_MAP_API
 static int
 case_map(OnigCaseFoldType* flagP, const OnigUChar** pp,
 	 const OnigUChar* end, OnigUChar* to, OnigUChar* to_end,
@@ -297,6 +298,7 @@ case_map(OnigCaseFoldType* flagP, const OnigUChar** pp,
   *flagP = flags;
   return (int )(to - to_start);
 }
+#endif
 
 OnigEncodingDefine(iso_8859_1, ISO_8859_1) = {
   onigenc_single_byte_mbc_enc_len,
@@ -315,7 +317,11 @@ OnigEncodingDefine(iso_8859_1, ISO_8859_1) = {
   onigenc_not_support_get_ctype_code_range,
   onigenc_single_byte_left_adjust_char_head,
   onigenc_always_true_is_allowed_reverse_match,
+#ifdef USE_CASE_MAP_API
   case_map,
+#else
+  NULL,
+#endif
   0,
   ONIGENC_FLAG_NONE,
 };
diff --git a/enc/iso_8859_10.c b/enc/iso_8859_10.c
index cae4be2db0367b..bf1c884cb23511 100644
--- a/enc/iso_8859_10.c
+++ b/enc/iso_8859_10.c
@@ -224,6 +224,7 @@ get_case_fold_codes_by_str(OnigCaseFoldType flag,
 	     flag, p, end, items);
 }
 
+#ifdef USE_CASE_MAP_API
 static int
 case_map(OnigCaseFoldType* flagP, const OnigUChar** pp,
 	 const OnigUChar* end, OnigUChar* to, OnigUChar* to_end,
@@ -269,6 +270,7 @@ case_map(OnigCaseFoldType* flagP, const OnigUChar** pp,
   *flagP = flags;
   return (int )(to - to_start);
 }
+#endif
 
 OnigEncodingDefine(iso_8859_10, ISO_8859_10) = {
   onigenc_single_byte_mbc_enc_len,
@@ -287,7 +289,11 @@ OnigEncodingDefine(iso_8859_10, ISO_8859_10) = {
   onigenc_not_support_get_ctype_code_range,
   onigenc_single_byte_left_adjust_char_head,
   onigenc_always_true_is_allowed_reverse_match,
+#ifdef USE_CASE_MAP_API
   case_map,
+#else
+  NULL,
+#endif
   0,
   ONIGENC_FLAG_NONE,
 };
diff --git a/enc/iso_8859_11.c b/enc/iso_8859_11.c
index b9c6119fd9a02b..403ae6499e0cf8 100644
--- a/enc/iso_8859_11.c
+++ b/enc/iso_8859_11.c
@@ -93,7 +93,11 @@ OnigEncodingDefine(iso_8859_11, ISO_8859_11) = {
   onigenc_not_support_get_ctype_code_range,
   onigenc_single_byte_left_adjust_char_head,
   onigenc_always_true_is_allowed_reverse_match,
+#ifdef USE_CASE_MAP_API
   onigenc_single_byte_ascii_only_case_map,
+#else
+  NULL,
+#endif
   0,
   ONIGENC_FLAG_NONE,
 };
diff --git a/enc/iso_8859_13.c b/enc/iso_8859_13.c
index fe1ddd7065e6ae..8c6e758b8066f3 100644
--- a/enc/iso_8859_13.c
+++ b/enc/iso_8859_13.c
@@ -217,6 +217,7 @@ get_case_fold_codes_by_str(OnigCaseFoldType flag,
 	     flag, p, end, items);
 }
 
+#ifdef USE_CASE_MAP_API
 static int
 case_map(OnigCaseFoldType* flagP, const OnigUChar** pp,
 	 const OnigUChar* end, OnigUChar* to, OnigUChar* to_end,
@@ -264,6 +265,7 @@ case_map(OnigCaseFoldType* flagP, const OnigUChar** pp,
   *flagP = flags;
   return (int )(to - to_start);
 }
+#endif
 
 OnigEncodingDefine(iso_8859_13, ISO_8859_13) = {
   onigenc_single_byte_mbc_enc_len,
@@ -282,7 +284,11 @@ OnigEncodingDefine(iso_8859_13, ISO_8859_13) = {
   onigenc_not_support_get_ctype_code_range,
   onigenc_single_byte_left_adjust_char_head,
   onigenc_always_true_is_allowed_reverse_match,
+#ifdef USE_CASE_MAP_API
   case_map,
+#else
+  NULL,
+#endif
   0,
   ONIGENC_FLAG_NONE,
 };
diff --git a/enc/iso_8859_14.c b/enc/iso_8859_14.c
index 647514a01626c0..21dffea76f087b 100644
--- a/enc/iso_8859_14.c
+++ b/enc/iso_8859_14.c
@@ -226,6 +226,7 @@ get_case_fold_codes_by_str(OnigCaseFoldType flag,
 	     flag, p, end, items);
 }
 
+#ifdef USE_CASE_MAP_API
 static int
 case_map(OnigCaseFoldType* flagP, const OnigUChar** pp,
 	 const OnigUChar* end, OnigUChar* to, OnigUChar* to_end,
@@ -280,6 +281,7 @@ case_map(OnigCaseFoldType* flagP, const OnigUChar** pp,
   *flagP = flags;
   return (int )(to - to_start);
 }
+#endif
 
 OnigEncodingDefine(iso_8859_14, ISO_8859_14) = {
   onigenc_single_byte_mbc_enc_len,
@@ -298,7 +300,11 @@ OnigEncodingDefine(iso_8859_14, ISO_8859_14) = {
   onigenc_not_support_get_ctype_code_range,
   onigenc_single_byte_left_adjust_char_head,
   onigenc_always_true_is_allowed_reverse_match,
+#ifdef USE_CASE_MAP_API
   case_map,
+#else
+  NULL,
+#endif
   0,
   ONIGENC_FLAG_NONE,
 };
diff --git a/enc/iso_8859_15.c b/enc/iso_8859_15.c
index 377a3afc7b15c5..dd6c29a6432455 100644
--- a/enc/iso_8859_15.c
+++ b/enc/iso_8859_15.c
@@ -220,6 +220,7 @@ get_case_fold_codes_by_str(OnigCaseFoldType flag,
 	     flag, p, end, items);
 }
 
+#ifdef USE_CASE_MAP_API
 static int
 case_map(OnigCaseFoldType* flagP, const OnigUChar** pp,
 	 const OnigUChar* end, OnigUChar* to, OnigUChar* to_end,
@@ -271,6 +272,7 @@ case_map(OnigCaseFoldType* flagP, const OnigUChar** pp,
   *flagP = flags;
   return (int )(to - to_start);
 }
+#endif
 
 OnigEncodingDefine(iso_8859_15, ISO_8859_15) = {
   onigenc_single_byte_mbc_enc_len,
@@ -289,7 +291,11 @@ OnigEncodingDefine(iso_8859_15, ISO_8859_15) = {
   onigenc_not_support_get_ctype_code_range,
   onigenc_single_byte_left_adjust_char_head,
   onigenc_always_true_is_allowed_reverse_match,
+#ifdef USE_CASE_MAP_API
   case_map,
+#else
+  NULL,
+#endif
   0,
   ONIGENC_FLAG_NONE,
 };
diff --git a/enc/iso_8859_16.c b/enc/iso_8859_16.c
index 135630eb73df46..aa7ce99fbac467 100644
--- a/enc/iso_8859_16.c
+++ b/enc/iso_8859_16.c
@@ -222,6 +222,7 @@ get_case_fold_codes_by_str(OnigCaseFoldType flag,
 	     flag, p, end, items);
 }
 
+#ifdef USE_CASE_MAP_API
 static int
 case_map(OnigCaseFoldType* flagP, const OnigUChar** pp,
 	 const OnigUChar* end, OnigUChar* to, OnigUChar* to_end,
@@ -275,6 +276,7 @@ case_map(OnigCaseFoldType* flagP, const OnigUChar** pp,
   *flagP = flags;
   return (int )(to - to_start);
 }
+#endif
 
 OnigEncodingDefine(iso_8859_16, ISO_8859_16) = {
   onigenc_single_byte_mbc_enc_len,
@@ -293,7 +295,11 @@ OnigEncodingDefine(iso_8859_16, ISO_8859_16) = {
   onigenc_not_support_get_ctype_code_range,
   onigenc_single_byte_left_adjust_char_head,
   onigenc_always_true_is_allowed_reverse_match,
+#ifdef USE_CASE_MAP_API
   case_map,
+#else
+  NULL,
+#endif
   0,
   ONIGENC_FLAG_NONE,
 };
diff --git a/enc/iso_8859_2.c b/enc/iso_8859_2.c
index 3a05c6320dbbeb..859073fd149cb4 100644
--- a/enc/iso_8859_2.c
+++ b/enc/iso_8859_2.c
@@ -220,6 +220,7 @@ is_code_ctype(OnigCodePoint code, unsigned int ctype, OnigEncoding enc ARG_UNUSE
     return FALSE;
 }
 
+#ifdef USE_CASE_MAP_API
 static int
 case_map(OnigCaseFoldType* flagP, const OnigUChar** pp,
 	 const OnigUChar* end, OnigUChar* to, OnigUChar* to_end,
@@ -266,6 +267,7 @@ case_map(OnigCaseFoldType* flagP, const OnigUChar** pp,
   *flagP = flags;
   return (int )(to - to_start);
 }
+#endif
 
 OnigEncodingDefine(iso_8859_2, ISO_8859_2) = {
   onigenc_single_byte_mbc_enc_len,
@@ -284,7 +286,11 @@ OnigEncodingDefine(iso_8859_2, ISO_8859_2) = {
   onigenc_not_support_get_ctype_code_range,
   onigenc_single_byte_left_adjust_char_head,
   onigenc_always_true_is_allowed_reverse_match,
+#ifdef USE_CASE_MAP_API
   case_map,
+#else
+  NULL,
+#endif
   0,
   ONIGENC_FLAG_NONE,
 };
diff --git a/enc/iso_8859_3.c b/enc/iso_8859_3.c
index 2a343eac638482..d8199d5125b19c 100644
--- a/enc/iso_8859_3.c
+++ b/enc/iso_8859_3.c
@@ -220,6 +220,7 @@ get_case_fold_codes_by_str(OnigCaseFoldType flag,
 	     flag, p, end, items);
 }
 
+#ifdef USE_CASE_MAP_API
 #define DOTLESS_i        (0xB9)
 #define I_WITH_DOT_ABOVE (0xA9)
 static int
@@ -276,6 +277,7 @@ case_map(OnigCaseFoldType* flagP, const OnigUChar** pp,
   *flagP = flags;
   return (int )(to - to_start);
 }
+#endif
 
 OnigEncodingDefine(iso_8859_3, ISO_8859_3) = {
   onigenc_single_byte_mbc_enc_len,
@@ -294,7 +296,11 @@ OnigEncodingDefine(iso_8859_3, ISO_8859_3) = {
   onigenc_not_support_get_ctype_code_range,
   onigenc_single_byte_left_adjust_char_head,
   onigenc_always_true_is_allowed_reverse_match,
+#ifdef USE_CASE_MAP_API
   case_map,
+#else
+  NULL,
+#endif
   0,
   ONIGENC_FLAG_NONE,
 };
diff --git a/enc/iso_8859_4.c b/enc/iso_8859_4.c
index e2134e8c0b27a5..5f01f0157556dd 100644
--- a/enc/iso_8859_4.c
+++ b/enc/iso_8859_4.c
@@ -223,6 +223,7 @@ get_case_fold_codes_by_str(OnigCaseFoldType flag,
 	     flag, p, end, items);
 }
 
+#ifdef USE_CASE_MAP_API
 static int
 case_map(OnigCaseFoldType* flagP, const OnigUChar** pp,
 	 const OnigUChar* end, OnigUChar* to, OnigUChar* to_end,
@@ -272,6 +273,7 @@ case_map(OnigCaseFoldType* flagP, const OnigUChar** pp,
   *flagP = flags;
   return (int )(to - to_start);
 }
+#endif
 
 OnigEncodingDefine(iso_8859_4, ISO_8859_4) = {
   onigenc_single_byte_mbc_enc_len,
@@ -290,7 +292,11 @@ OnigEncodingDefine(iso_8859_4, ISO_8859_4) = {
   onigenc_not_support_get_ctype_code_range,
   onigenc_single_byte_left_adjust_char_head,
   onigenc_always_true_is_allowed_reverse_match,
+#ifdef USE_CASE_MAP_API
   case_map,
+#else
+  NULL,
+#endif
   0,
   ONIGENC_FLAG_NONE,
 };
diff --git a/enc/iso_8859_5.c b/enc/iso_8859_5.c
index 6fafc358233eb9..8223fc0ec706c8 100644
--- a/enc/iso_8859_5.c
+++ b/enc/iso_8859_5.c
@@ -209,6 +209,7 @@ get_case_fold_codes_by_str(OnigCaseFoldType flag,
 	     flag, p, end, items);
 }
 
+#ifdef USE_CASE_MAP_API
 static int
 case_map(OnigCaseFoldType* flagP, const OnigUChar** pp,
 	 const OnigUChar* end, OnigUChar* to, OnigUChar* to_end,
@@ -240,6 +241,7 @@ case_map(OnigCaseFoldType* flagP, const OnigUChar** pp,
   *flagP = flags;
   return (int )(to - to_start);
 }
+#endif
 
 OnigEncodingDefine(iso_8859_5, ISO_8859_5) = {
   onigenc_single_byte_mbc_enc_len,
@@ -258,7 +260,11 @@ OnigEncodingDefine(iso_8859_5, ISO_8859_5) = {
   onigenc_not_support_get_ctype_code_range,
   onigenc_single_byte_left_adjust_char_head,
   onigenc_always_true_is_allowed_reverse_match,
+#ifdef USE_CASE_MAP_API
   case_map,
+#else
+  NULL,
+#endif
   0,
   ONIGENC_FLAG_NONE,
 };
diff --git a/enc/iso_8859_6.c b/enc/iso_8859_6.c
index cdb74054d1e312..78543ea307d221 100644
--- a/enc/iso_8859_6.c
+++ b/enc/iso_8859_6.c
@@ -93,7 +93,11 @@ OnigEncodingDefine(iso_8859_6, ISO_8859_6) = {
   onigenc_not_support_get_ctype_code_range,
   onigenc_single_byte_left_adjust_char_head,
   onigenc_always_true_is_allowed_reverse_match,
+#ifdef USE_CASE_MAP_API
   onigenc_single_byte_ascii_only_case_map,
+#else
+  NULL,
+#endif
   0,
   ONIGENC_FLAG_NONE,
 };
diff --git a/enc/iso_8859_7.c b/enc/iso_8859_7.c
index ac973f74ba51ef..e84f5c3460ad4e 100644
--- a/enc/iso_8859_7.c
+++ b/enc/iso_8859_7.c
@@ -205,6 +205,7 @@ get_case_fold_codes_by_str(OnigCaseFoldType flag,
 	     flag, p, end, items);
 }
 
+#ifdef USE_CASE_MAP_API
 static int
 case_map(OnigCaseFoldType* flagP, const OnigUChar** pp,
 	 const OnigUChar* end, OnigUChar* to, OnigUChar* to_end,
@@ -259,6 +260,7 @@ case_map(OnigCaseFoldType* flagP, const OnigUChar** pp,
   *flagP = flags;
   return (int )(to - to_start);
 }
+#endif
 
 OnigEncodingDefine(iso_8859_7, ISO_8859_7) = {
   onigenc_single_byte_mbc_enc_len,
@@ -277,7 +279,11 @@ OnigEncodingDefine(iso_8859_7, ISO_8859_7) = {
   onigenc_not_support_get_ctype_code_range,
   onigenc_single_byte_left_adjust_char_head,
   onigenc_always_true_is_allowed_reverse_match,
+#ifdef USE_CASE_MAP_API
   case_map,
+#else
+  NULL,
+#endif
   0,
   ONIGENC_FLAG_NONE,
 };
diff --git a/enc/iso_8859_8.c b/enc/iso_8859_8.c
index e256855f2130a7..b757a283de15a0 100644
--- a/enc/iso_8859_8.c
+++ b/enc/iso_8859_8.c
@@ -93,7 +93,11 @@ OnigEncodingDefine(iso_8859_8, ISO_8859_8) = {
   onigenc_not_support_get_ctype_code_range,
   onigenc_single_byte_left_adjust_char_head,
   onigenc_always_true_is_allowed_reverse_match,
+#ifdef USE_CASE_MAP_API
   onigenc_single_byte_ascii_only_case_map,
+#else
+  NULL,
+#endif
   0,
   ONIGENC_FLAG_NONE,
 };
diff --git a/enc/iso_8859_9.c b/enc/iso_8859_9.c
index 004eec310fcd52..f15953963bf4de 100644
--- a/enc/iso_8859_9.c
+++ b/enc/iso_8859_9.c
@@ -213,6 +213,7 @@ get_case_fold_codes_by_str(OnigCaseFoldType flag,
 	     flag, p, end, items);
 }
 
+#ifdef USE_CASE_MAP_API
 #define DOTLESS_i        (0xFD)
 #define I_WITH_DOT_ABOVE (0xDD)
 static int
@@ -265,6 +266,7 @@ case_map(OnigCaseFoldType* flagP, const OnigUChar** pp,
   *flagP = flags;
   return (int )(to - to_start);
 }
+#endif
 
 OnigEncodingDefine(iso_8859_9, ISO_8859_9) = {
   onigenc_single_byte_mbc_enc_len,
@@ -283,7 +285,11 @@ OnigEncodingDefine(iso_8859_9, ISO_8859_9) = {
   onigenc_not_support_get_ctype_code_range,
   onigenc_single_byte_left_adjust_char_head,
   onigenc_always_true_is_allowed_reverse_match,
+#ifdef USE_CASE_MAP_API
   case_map,
+#else
+  NULL,
+#endif
   0,
   ONIGENC_FLAG_NONE,
 };
diff --git a/enc/koi8_r.c b/enc/koi8_r.c
index a52097577416a1..39f24824651275 100644
--- a/enc/koi8_r.c
+++ b/enc/koi8_r.c
@@ -214,7 +214,11 @@ OnigEncodingDefine(koi8_r, KOI8_R) = {
   onigenc_not_support_get_ctype_code_range,
   onigenc_single_byte_left_adjust_char_head,
   onigenc_always_true_is_allowed_reverse_match,
+#ifdef USE_CASE_MAP_API
   onigenc_single_byte_ascii_only_case_map,
+#else
+  NULL,
+#endif
   0,
   ONIGENC_FLAG_NONE,
 };
diff --git a/enc/koi8_u.c b/enc/koi8_u.c
index 50bb78bd04841d..8cd890dd16a041 100644
--- a/enc/koi8_u.c
+++ b/enc/koi8_u.c
@@ -218,7 +218,11 @@ OnigEncodingDefine(koi8_u, KOI8_U) = {
   onigenc_not_support_get_ctype_code_range,
   onigenc_single_byte_left_adjust_char_head,
   onigenc_always_true_is_allowed_reverse_match,
+#ifdef USE_CASE_MAP_API
   onigenc_single_byte_ascii_only_case_map,
+#else
+  NULL,
+#endif
   0,
   ONIGENC_FLAG_NONE,
 };
diff --git a/enc/shift_jis.c b/enc/shift_jis.c
index f1355d2d95fcb4..48f648868af13d 100644
--- a/enc/shift_jis.c
+++ b/enc/shift_jis.c
@@ -47,7 +47,11 @@ OnigEncodingDefine(shift_jis, Shift_JIS) = {
   get_ctype_code_range,
   left_adjust_char_head,
   is_allowed_reverse_match,
+#ifdef USE_CASE_MAP_API
   onigenc_ascii_only_case_map,
+#else
+  NULL,
+#endif
   0,
   ONIGENC_FLAG_NONE,
 };
diff --git a/enc/unicode.c b/enc/unicode.c
index 07497cdbe46731..5bc806863e8f55 100644
--- a/enc/unicode.c
+++ b/enc/unicode.c
@@ -655,6 +655,7 @@ onigenc_unicode_get_case_fold_codes_by_str(OnigEncoding enc,
   return n;
 }
 
+#ifdef USE_CASE_MAP_API
 /* length in bytes for three characters in UTF-32; e.g. needed for ffi (U+FB03) */
 #define CASE_MAPPING_SLACK 12
 #define MODIFIED (flags |= ONIGENC_CASE_MODIFIED)
@@ -798,6 +799,7 @@ onigenc_unicode_case_map(OnigCaseFoldType* flagP,
   *flagP = flags;
   return (int )(to - to_start);
 }
+#endif
 
 const char onigenc_unicode_version_string[] =
 #ifdef ONIG_UNICODE_VERSION_STRING
diff --git a/enc/us_ascii.c b/enc/us_ascii.c
index 08f9072c435591..253ee695724159 100644
--- a/enc/us_ascii.c
+++ b/enc/us_ascii.c
@@ -32,7 +32,11 @@ OnigEncodingDefine(us_ascii, US_ASCII) = {
   onigenc_not_support_get_ctype_code_range,
   onigenc_single_byte_left_adjust_char_head,
   onigenc_always_true_is_allowed_reverse_match,
+#ifdef USE_CASE_MAP_API
   onigenc_single_byte_ascii_only_case_map,
+#else
+  NULL,
+#endif
   ENCINDEX_US_ASCII,
   ONIGENC_FLAG_NONE,
 };
diff --git a/enc/utf_16be.c b/enc/utf_16be.c
index f9dd7119d65a0e..0086040b5d5bd9 100644
--- a/enc/utf_16be.c
+++ b/enc/utf_16be.c
@@ -249,7 +249,11 @@ OnigEncodingDefine(utf_16be, UTF_16BE) = {
   onigenc_utf16_32_get_ctype_code_range,
   utf16be_left_adjust_char_head,
   onigenc_always_false_is_allowed_reverse_match,
+#ifdef USE_CASE_MAP_API
   onigenc_unicode_case_map,
+#else
+  NULL,
+#endif
   0,
   ONIGENC_FLAG_UNICODE,
 };
diff --git a/enc/utf_16le.c b/enc/utf_16le.c
index 2c8438d0be2554..ca0fce53872045 100644
--- a/enc/utf_16le.c
+++ b/enc/utf_16le.c
@@ -242,7 +242,11 @@ OnigEncodingDefine(utf_16le, UTF_16LE) = {
   onigenc_utf16_32_get_ctype_code_range,
   utf16le_left_adjust_char_head,
   onigenc_always_false_is_allowed_reverse_match,
+#ifdef USE_CASE_MAP_API
   onigenc_unicode_case_map,
+#else
+  NULL,
+#endif
   0,
   ONIGENC_FLAG_UNICODE,
 };
diff --git a/enc/utf_32be.c b/enc/utf_32be.c
index 17841e52a4e82d..e05cfaf1b2fdf8 100644
--- a/enc/utf_32be.c
+++ b/enc/utf_32be.c
@@ -199,7 +199,11 @@ OnigEncodingDefine(utf_32be, UTF_32BE) = {
   onigenc_utf16_32_get_ctype_code_range,
   utf32be_left_adjust_char_head,
   onigenc_always_false_is_allowed_reverse_match,
+#ifdef USE_CASE_MAP_API
   onigenc_unicode_case_map,
+#else
+  NULL,
+#endif
   0,
   ONIGENC_FLAG_UNICODE,
 };
diff --git a/enc/utf_32le.c b/enc/utf_32le.c
index 18b798f102c5d1..651efdcec57790 100644
--- a/enc/utf_32le.c
+++ b/enc/utf_32le.c
@@ -199,7 +199,11 @@ OnigEncodingDefine(utf_32le, UTF_32LE) = {
   onigenc_utf16_32_get_ctype_code_range,
   utf32le_left_adjust_char_head,
   onigenc_always_false_is_allowed_reverse_match,
+#ifdef USE_CASE_MAP_API
   onigenc_unicode_case_map,
+#else
+  NULL,
+#endif
   0,
   ONIGENC_FLAG_UNICODE,
 };
diff --git a/enc/utf_8.c b/enc/utf_8.c
index cdf2510d84c829..ae7c98469d50bd 100644
--- a/enc/utf_8.c
+++ b/enc/utf_8.c
@@ -431,7 +431,11 @@ OnigEncodingDefine(utf_8, UTF_8) = {
   get_ctype_code_range,
   left_adjust_char_head,
   onigenc_always_true_is_allowed_reverse_match,
+#ifdef USE_CASE_MAP_API
   onigenc_unicode_case_map,
+#else
+  NULL,
+#endif
   ENCINDEX_UTF_8,
   ONIGENC_FLAG_UNICODE,
 };
diff --git a/enc/windows_1250.c b/enc/windows_1250.c
index daf23e9d1e6e6a..d38d50a01d370d 100644
--- a/enc/windows_1250.c
+++ b/enc/windows_1250.c
@@ -190,6 +190,7 @@ cp1250_get_case_fold_codes_by_str(OnigCaseFoldType flag,
 	     flag, p, end, items);
 }
 
+#ifdef USE_CASE_MAP_API
 static int
 case_map(OnigCaseFoldType* flagP, const OnigUChar** pp,
 	 const OnigUChar* end, OnigUChar* to, OnigUChar* to_end,
@@ -239,6 +240,7 @@ case_map(OnigCaseFoldType* flagP, const OnigUChar** pp,
   *flagP = flags;
   return (int )(to - to_start);
 }
+#endif
 
 OnigEncodingDefine(windows_1250, Windows_1250) = {
   onigenc_single_byte_mbc_enc_len,
@@ -257,7 +259,11 @@ OnigEncodingDefine(windows_1250, Windows_1250) = {
   onigenc_not_support_get_ctype_code_range,
   onigenc_single_byte_left_adjust_char_head,
   onigenc_always_true_is_allowed_reverse_match,
+#ifdef USE_CASE_MAP_API
   case_map,
+#else
+  NULL,
+#endif
   0,
   ONIGENC_FLAG_NONE,
 };
diff --git a/enc/windows_1251.c b/enc/windows_1251.c
index 6c892c1b8ce39a..81641d0337f2b2 100644
--- a/enc/windows_1251.c
+++ b/enc/windows_1251.c
@@ -180,6 +180,7 @@ cp1251_get_case_fold_codes_by_str(OnigCaseFoldType flag,
 	     flag, p, end, items);
 }
 
+#ifdef USE_CASE_MAP_API
 static int
 case_map(OnigCaseFoldType* flagP, const OnigUChar** pp,
 	 const OnigUChar* end, OnigUChar* to, OnigUChar* to_end,
@@ -221,6 +222,7 @@ case_map(OnigCaseFoldType* flagP, const OnigUChar** pp,
   *flagP = flags;
   return (int )(to - to_start);
 }
+#endif
 
 OnigEncodingDefine(windows_1251, Windows_1251) = {
   onigenc_single_byte_mbc_enc_len,
@@ -239,7 +241,11 @@ OnigEncodingDefine(windows_1251, Windows_1251) = {
   onigenc_not_support_get_ctype_code_range,
   onigenc_single_byte_left_adjust_char_head,
   onigenc_always_true_is_allowed_reverse_match,
+#ifdef USE_CASE_MAP_API
   case_map,
+#else
+  NULL,
+#endif
   0,
   ONIGENC_FLAG_NONE,
 };
diff --git a/enc/windows_1252.c b/enc/windows_1252.c
index b685878d3fc5d7..6aece95c0ab2ae 100644
--- a/enc/windows_1252.c
+++ b/enc/windows_1252.c
@@ -181,6 +181,7 @@ cp1252_get_case_fold_codes_by_str(OnigCaseFoldType flag,
 	     flag, p, end, items);
 }
 
+#ifdef USE_CASE_MAP_API
 static int
 case_map(OnigCaseFoldType* flagP, const OnigUChar** pp,
 	 const OnigUChar* end, OnigUChar* to, OnigUChar* to_end,
@@ -228,6 +229,7 @@ case_map(OnigCaseFoldType* flagP, const OnigUChar** pp,
   *flagP = flags;
   return (int )(to - to_start);
 }
+#endif
 
 OnigEncodingDefine(windows_1252, Windows_1252) = {
   onigenc_single_byte_mbc_enc_len,
@@ -246,7 +248,11 @@ OnigEncodingDefine(windows_1252, Windows_1252) = {
   onigenc_not_support_get_ctype_code_range,
   onigenc_single_byte_left_adjust_char_head,
   onigenc_always_true_is_allowed_reverse_match,
+#ifdef USE_CASE_MAP_API
   case_map,
+#else
+  NULL,
+#endif
   0,
   ONIGENC_FLAG_NONE,
 };
diff --git a/enc/windows_1253.c b/enc/windows_1253.c
index b2a43581c39240..c95ea3f41ccd9f 100644
--- a/enc/windows_1253.c
+++ b/enc/windows_1253.c
@@ -213,6 +213,7 @@ get_case_fold_codes_by_str(OnigCaseFoldType flag,
 	     flag, p, end, items);
 }
 
+#ifdef USE_CASE_MAP_API
 static int
 case_map(OnigCaseFoldType* flagP, const OnigUChar** pp,
 	 const OnigUChar* end, OnigUChar* to, OnigUChar* to_end,
@@ -272,6 +273,7 @@ case_map(OnigCaseFoldType* flagP, const OnigUChar** pp,
   *flagP = flags;
   return (int )(to - to_start);
 }
+#endif
 
 OnigEncodingDefine(windows_1253, Windows_1253) = {
   onigenc_single_byte_mbc_enc_len,
@@ -290,7 +292,11 @@ OnigEncodingDefine(windows_1253, Windows_1253) = {
   onigenc_not_support_get_ctype_code_range,
   onigenc_single_byte_left_adjust_char_head,
   onigenc_always_true_is_allowed_reverse_match,
+#ifdef USE_CASE_MAP_API
   case_map,
+#else
+  NULL,
+#endif
   0,
   ONIGENC_FLAG_NONE,
 };
diff --git a/enc/windows_1254.c b/enc/windows_1254.c
index 5e6d92d3d2680e..c8d5991686a0b3 100644
--- a/enc/windows_1254.c
+++ b/enc/windows_1254.c
@@ -221,6 +221,7 @@ get_case_fold_codes_by_str(OnigCaseFoldType flag,
 	     flag, p, end, items);
 }
 
+#ifdef USE_CASE_MAP_API
 #define DOTLESS_i        (0xFD)
 #define I_WITH_DOT_ABOVE (0xDD)
 static int
@@ -277,6 +278,7 @@ case_map(OnigCaseFoldType* flagP, const OnigUChar** pp,
   *flagP = flags;
   return (int )(to - to_start);
 }
+#endif
 
 OnigEncodingDefine(windows_1254, Windows_1254) = {
   onigenc_single_byte_mbc_enc_len,
@@ -295,7 +297,11 @@ OnigEncodingDefine(windows_1254, Windows_1254) = {
   onigenc_not_support_get_ctype_code_range,
   onigenc_single_byte_left_adjust_char_head,
   onigenc_always_true_is_allowed_reverse_match,
+#ifdef USE_CASE_MAP_API
   case_map,
+#else
+  NULL,
+#endif
   0,
   ONIGENC_FLAG_NONE,
 };
diff --git a/enc/windows_1257.c b/enc/windows_1257.c
index ada03b72bf01cf..def13c8c49fed0 100644
--- a/enc/windows_1257.c
+++ b/enc/windows_1257.c
@@ -225,6 +225,7 @@ get_case_fold_codes_by_str(OnigCaseFoldType flag,
 	     flag, p, end, items);
 }
 
+#ifdef USE_CASE_MAP_API
 #define DOTLESS_i        (0xB9)
 #define I_WITH_DOT_ABOVE (0xA9)
 static int
@@ -279,6 +280,7 @@ case_map(OnigCaseFoldType* flagP, const OnigUChar** pp,
   *flagP = flags;
   return (int )(to - to_start);
 }
+#endif
 
 OnigEncodingDefine(windows_1257, Windows_1257) = {
   onigenc_single_byte_mbc_enc_len,
@@ -297,7 +299,11 @@ OnigEncodingDefine(windows_1257, Windows_1257) = {
   onigenc_not_support_get_ctype_code_range,
   onigenc_single_byte_left_adjust_char_head,
   onigenc_always_true_is_allowed_reverse_match,
+#ifdef USE_CASE_MAP_API
   case_map,
+#else
+  NULL,
+#endif
   0,
   ONIGENC_FLAG_NONE,
 };
diff --git a/enc/windows_31j.c b/enc/windows_31j.c
index 1eb859596a3bc3..cd8bd83fddf693 100644
--- a/enc/windows_31j.c
+++ b/enc/windows_31j.c
@@ -48,7 +48,11 @@ OnigEncodingDefine(windows_31j, Windows_31J) = {
   get_ctype_code_range,
   left_adjust_char_head,
   is_allowed_reverse_match,
+#ifdef USE_CASE_MAP_API
   onigenc_ascii_only_case_map,
+#else
+  NULL,
+#endif
   0,
   ONIGENC_FLAG_NONE,
 };
diff --git a/include/ruby/onigmo.h b/include/ruby/onigmo.h
index db290cd47a644d..9dcddee829a86f 100644
--- a/include/ruby/onigmo.h
+++ b/include/ruby/onigmo.h
@@ -4,8 +4,8 @@
   onigmo.h - Onigmo (Oniguruma-mod) (regular expression library)
 **********************************************************************/
 /*-
- * Copyright (c) 2002-2009  K.Kosako  <sndgk393 AT ybb DOT ne DOT jp>
- * Copyright (c) 2011-2017  K.Takata  <kentkt AT csc DOT jp>
+ * Copyright (c) 2002-2016  K.Kosako  <sndgk393 AT ybb DOT ne DOT jp>
+ * Copyright (c) 2011-2019  K.Takata  <kentkt AT csc DOT jp>
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -38,8 +38,8 @@ extern "C" {
 #endif
 
 #define ONIGMO_VERSION_MAJOR   6
-#define ONIGMO_VERSION_MINOR   1
-#define ONIGMO_VERSION_TEENY   3
+#define ONIGMO_VERSION_MINOR   2
+#define ONIGMO_VERSION_TEENY   0
 
 #ifndef ONIG_EXTERN
 # ifdef RUBY_EXTERN
@@ -789,8 +789,8 @@ typedef struct re_pattern_buffer {
   unsigned char *exact;
   unsigned char *exact_end;
   unsigned char  map[ONIG_CHAR_TABLE_SIZE]; /* used as BM skip or char-map */
-  int           *int_map;                   /* BM skip for exact_len > 255 */
-  int           *int_map_backward;          /* BM skip for backward search */
+  int           *reserved1;
+  int           *reserved2;
   OnigDistance   dmin;                      /* min-distance of exact or map */
   OnigDistance   dmax;                      /* max-distance of exact or map */
 
diff --git a/regcomp.c b/regcomp.c
index 0ecf162556b777..18b2c97eb6381c 100644
--- a/regcomp.c
+++ b/regcomp.c
@@ -2,8 +2,8 @@
   regcomp.c -  Onigmo (Oniguruma-mod) (regular expression library)
 **********************************************************************/
 /*-
- * Copyright (c) 2002-2013  K.Kosako  <sndgk393 AT ybb DOT ne DOT jp>
- * Copyright (c) 2011-2016  K.Takata  <kentkt AT csc DOT jp>
+ * Copyright (c) 2002-2018  K.Kosako  <sndgk393 AT ybb DOT ne DOT jp>
+ * Copyright (c) 2011-2019  K.Takata  <kentkt AT csc DOT jp>
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -4216,7 +4216,7 @@ setup_tree(Node* node, regex_t* reg, int state, ScanEnv* env)
 /* set skip map for Sunday's quick search */
 static int
 set_bm_skip(UChar* s, UChar* end, regex_t* reg,
-            UChar skip[], int** int_skip, int ignore_case)
+            UChar skip[], int ignore_case)
 {
   OnigDistance i, len;
   int clen, flen, n, j, k;
@@ -4225,94 +4225,60 @@ set_bm_skip(UChar* s, UChar* end, regex_t* reg,
   OnigEncoding enc = reg->enc;
 
   len = end - s;
-  if (len < ONIG_CHAR_TABLE_SIZE) {
-    if (ignore_case) {
-      for (i = 0; i < len; i += clen) {
-        p = s + i;
-        n = ONIGENC_GET_CASE_FOLD_CODES_BY_STR(enc, reg->case_fold_flag,
-            p, end, items);
-        clen = enclen(enc, p, end);
-        if (p + clen > end)
-          clen = (int )(end - p);
-
-        for (j = 0; j < n; j++) {
-          if ((items[j].code_len != 1) || (items[j].byte_len != clen)) {
-            /* Different length isn't supported. Stop optimization at here. */
-            end = p;
-            goto endcheck;
-          }
-          flen = ONIGENC_CODE_TO_MBC(enc, items[j].code[0], buf);
-          if (flen != clen) {
-            /* Different length isn't supported. Stop optimization at here. */
-            end = p;
-            goto endcheck;
-          }
-        }
-      }
-endcheck:
-      ;
-    }
-
-    len = end - s;
-    for (i = 0; i < ONIG_CHAR_TABLE_SIZE; i++)
-      skip[i] = (UChar )(len + 1);
-    n = 0;
-    for (i = 0; i < len; i += clen) {
-      p = s + i;
-      if (ignore_case)
-        n = ONIGENC_GET_CASE_FOLD_CODES_BY_STR(enc, reg->case_fold_flag,
-                                               p, end, items);
-      clen = enclen(enc, p, end);
-      if (p + clen > end)
-        clen = (int )(end - p);
-
-      for (j = 0; j < clen; j++) {
-        skip[s[i + j]] = (UChar )(len - i - j);
-        for (k = 0; k < n; k++) {
-          ONIGENC_CODE_TO_MBC(enc, items[k].code[0], buf);
-          skip[buf[j]] = (UChar )(len - i - j);
-        }
-      }
-    }
-  }
-  else {
-# if OPT_EXACT_MAXLEN < ONIG_CHAR_TABLE_SIZE
+  if (len >= ONIG_CHAR_TABLE_SIZE) {
     /* This should not happen. */
     return ONIGERR_TYPE_BUG;
-# else
-    if (IS_NULL(*int_skip)) {
-      *int_skip = (int* )xmalloc(sizeof(int) * ONIG_CHAR_TABLE_SIZE);
-      if (IS_NULL(*int_skip)) return ONIGERR_MEMORY;
-    }
-    for (i = 0; i < ONIG_CHAR_TABLE_SIZE; i++) (*int_skip)[i] = (int )(len + 1);
+  }
 
-    n = 0;
+  if (ignore_case) {
     for (i = 0; i < len; i += clen) {
       p = s + i;
-      if (ignore_case)
-        n = ONIGENC_GET_CASE_FOLD_CODES_BY_STR(enc, reg->case_fold_flag,
-                                               p, end, items);
+      n = ONIGENC_GET_CASE_FOLD_CODES_BY_STR(enc, reg->case_fold_flag,
+	  p, end, items);
       clen = enclen(enc, p, end);
       if (p + clen > end)
         clen = (int )(end - p);
 
       for (j = 0; j < n; j++) {
-        if ((items[j].code_len != 1) || (items[j].byte_len != clen))
-          return 1;  /* different length isn't supported. */
-        flen = ONIGENC_CODE_TO_MBC(enc, items[j].code[0], buf[j]);
-        if (flen != clen)
-          return 1;  /* different length isn't supported. */
+	if ((items[j].code_len != 1) || (items[j].byte_len != clen)) {
+	  /* Different length isn't supported. Stop optimization at here. */
+	  end = p;
+	  goto endcheck;
+	}
+	flen = ONIGENC_CODE_TO_MBC(enc, items[j].code[0], buf);
+	if (flen != clen) {
+	  /* Different length isn't supported. Stop optimization at here. */
+	  end = p;
+	  goto endcheck;
+	}
       }
-      for (j = 0; j < clen; j++) {
-        (*int_skip)[s[i + j]] = (int )(len - i - j);
-        for (k = 0; k < n; k++) {
-          (*int_skip)[buf[k][j]] = (int )(len - i - j);
-        }
+    }
+endcheck:
+    len = end - s;
+  }
+
+  for (i = 0; i < ONIG_CHAR_TABLE_SIZE; i++)
+    skip[i] = (UChar )(len + 1);
+  n = 0;
+  for (i = 0; i < len; i += clen) {
+    p = s + i;
+    if (ignore_case)
+      n = ONIGENC_GET_CASE_FOLD_CODES_BY_STR(enc, reg->case_fold_flag,
+					     p, end, items);
+    clen = enclen(enc, p, end);
+    if (p + clen > end)
+      clen = (int )(end - p);
+
+    for (j = 0; j < clen; j++) {
+      skip[s[i + j]] = (UChar )(len - i - j);
+      for (k = 0; k < n; k++) {
+	ONIGENC_CODE_TO_MBC(enc, items[k].code[0], buf);
+	skip[buf[j]] = (UChar )(len - i - j);
       }
     }
-# endif
   }
-  return (int)len;
+
+  return (int )len;
 }
 
 typedef struct {
@@ -5299,7 +5265,7 @@ set_optimize_exact_info(regex_t* reg, OptExactInfo* e)
   if (e->ignore_case > 0) {
     if (e->len >= 3 || (e->len >= 2 && allow_reverse)) {
       e->len = set_bm_skip(reg->exact, reg->exact_end, reg,
-                      reg->map, &(reg->int_map), 1);
+                           reg->map, 1);
       reg->exact_end = reg->exact + e->len;
       if (e->len >= 3) {
         reg->optimize = (allow_reverse != 0
@@ -5318,7 +5284,7 @@ set_optimize_exact_info(regex_t* reg, OptExactInfo* e)
   else {
     if (e->len >= 3 || (e->len >= 2 && allow_reverse)) {
       set_bm_skip(reg->exact, reg->exact_end, reg,
-                  reg->map, &(reg->int_map), 0);
+                  reg->map, 0);
       reg->optimize = (allow_reverse != 0
                      ? ONIG_OPTIMIZE_EXACT_BM : ONIG_OPTIMIZE_EXACT_BM_NOT_REV);
     }
@@ -5601,8 +5567,6 @@ onig_free_body(regex_t* reg)
   if (IS_NOT_NULL(reg)) {
     xfree(reg->p);
     xfree(reg->exact);
-    xfree(reg->int_map);
-    xfree(reg->int_map_backward);
     xfree(reg->repeat_range);
     onig_free(reg->chain);
 
@@ -5649,14 +5613,6 @@ onig_reg_copy(regex_t** nreg, regex_t* oreg)
       (reg)->exact_end = (reg)->exact + exact_size;
     }
 
-    if (IS_NOT_NULL(reg->int_map)) {
-      if (COPY_FAILED(int_map, sizeof(int) * ONIG_CHAR_TABLE_SIZE))
-        goto err_int_map;
-    }
-    if (IS_NOT_NULL(reg->int_map_backward)) {
-      if (COPY_FAILED(int_map_backward, sizeof(int) * ONIG_CHAR_TABLE_SIZE))
-        goto err_int_map_backward;
-    }
     if (IS_NOT_NULL(reg->p)) {
       if (COPY_FAILED(p, reg->alloc))
         goto err_p;
@@ -5683,10 +5639,6 @@ onig_reg_copy(regex_t** nreg, regex_t* oreg)
   err_repeat_range:
     xfree(reg->p);
   err_p:
-    xfree(reg->int_map_backward);
-  err_int_map_backward:
-    xfree(reg->int_map);
-  err_int_map:
     xfree(reg->exact);
   err:
     xfree(reg);
@@ -5703,8 +5655,6 @@ onig_memsize(const regex_t *reg)
     if (IS_NULL(reg)) return 0;
     if (IS_NOT_NULL(reg->p))                size += reg->alloc;
     if (IS_NOT_NULL(reg->exact))            size += reg->exact_end - reg->exact;
-    if (IS_NOT_NULL(reg->int_map))          size += sizeof(int) * ONIG_CHAR_TABLE_SIZE;
-    if (IS_NOT_NULL(reg->int_map_backward)) size += sizeof(int) * ONIG_CHAR_TABLE_SIZE;
     if (IS_NOT_NULL(reg->repeat_range))     size += reg->repeat_range_alloc * sizeof(OnigRepeatRange);
     if (IS_NOT_NULL(reg->chain))            size += onig_memsize(reg->chain);
 
@@ -5969,6 +5919,12 @@ onig_reg_init(regex_t* reg, OnigOptionType option,
   if (IS_NULL(reg))
     return ONIGERR_INVALID_ARGUMENT;
 
+  (reg)->exact            = (UChar* )NULL;
+  (reg)->chain            = (regex_t* )NULL;
+  (reg)->p                = (UChar* )NULL;
+  (reg)->name_table       = (void* )NULL;
+  (reg)->repeat_range     = (OnigRepeatRange* )NULL;
+
   if (ONIGENC_IS_UNDEF(enc))
     return ONIGERR_DEFAULT_ENCODING_IS_NOT_SET;
 
@@ -5988,15 +5944,9 @@ onig_reg_init(regex_t* reg, OnigOptionType option,
   (reg)->options          = option;
   (reg)->syntax           = syntax;
   (reg)->optimize         = 0;
-  (reg)->exact            = (UChar* )NULL;
-  (reg)->int_map          = (int* )NULL;
-  (reg)->int_map_backward = (int* )NULL;
-  (reg)->chain            = (regex_t* )NULL;
 
-  (reg)->p                = (UChar* )NULL;
   (reg)->alloc            = 0;
   (reg)->used             = 0;
-  (reg)->name_table       = (void* )NULL;
 
   (reg)->case_fold_flag   = case_fold_flag;
 
diff --git a/regenc.c b/regenc.c
index 823aacc28e615b..c595f44b29e36d 100644
--- a/regenc.c
+++ b/regenc.c
@@ -3,7 +3,7 @@
 **********************************************************************/
 /*-
  * Copyright (c) 2002-2007  K.Kosako  <sndgk393 AT ybb DOT ne DOT jp>
- * Copyright (c) 2011-2016  K.Takata  <kentkt AT csc DOT jp>
+ * Copyright (c) 2011-2019  K.Takata  <kentkt AT csc DOT jp>
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -640,18 +640,19 @@ onigenc_single_byte_mbc_to_code(const UChar* p, const UChar* end ARG_UNUSED,
 }
 
 extern int
-onigenc_single_byte_code_to_mbclen(OnigCodePoint code ARG_UNUSED, OnigEncoding enc ARG_UNUSED)
+onigenc_single_byte_code_to_mbclen(OnigCodePoint code, OnigEncoding enc ARG_UNUSED)
 {
+  if (code > 0xff)
+    return ONIGERR_INVALID_CODE_POINT_VALUE;
   return 1;
 }
 
 extern int
 onigenc_single_byte_code_to_mbc(OnigCodePoint code, UChar *buf, OnigEncoding enc ARG_UNUSED)
 {
-#ifdef RUBY
-  if (code > 0xff)
-    rb_raise(rb_eRangeError, "%u out of char range", code);
-#endif
+  if (code > 0xff) {
+    return ONIGERR_INVALID_CODE_POINT_VALUE;
+  }
   *buf = (UChar )(code & 0xff);
   return 1;
 }
@@ -966,6 +967,7 @@ onigenc_property_list_add_property(UChar* name, const OnigCodePoint* prop,
 }
 #endif
 
+#ifdef USE_CASE_MAP_API
 extern int
 onigenc_ascii_only_case_map(OnigCaseFoldType* flagP, const OnigUChar** pp, const OnigUChar* end,
                             OnigUChar* to, OnigUChar* to_end, const struct OnigEncodingTypeST* enc)
@@ -1027,3 +1029,4 @@ onigenc_single_byte_ascii_only_case_map(OnigCaseFoldType* flagP, const OnigUChar
   *flagP = flags;
   return (int )(to - to_start);
 }
+#endif
diff --git a/regenc.h b/regenc.h
index 4fbe403b6301d8..fe0440dd740e9b 100644
--- a/regenc.h
+++ b/regenc.h
@@ -5,7 +5,7 @@
 **********************************************************************/
 /*-
  * Copyright (c) 2002-2008  K.Kosako  <sndgk393 AT ybb DOT ne DOT jp>
- * Copyright (c) 2011-2016  K.Takata  <kentkt AT csc DOT jp>
+ * Copyright (c) 2011-2019  K.Takata  <kentkt AT csc DOT jp>
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -134,11 +134,13 @@ typedef struct {
 #define roomof(x, y) (((x) + (y) - 1) / (y))
 #define type_roomof(x, y) roomof(sizeof(x), sizeof(y))
 
+/* config */
 #define USE_CRNL_AS_LINE_TERMINATOR
 #define USE_UNICODE_PROPERTIES
 #define USE_UNICODE_AGE_PROPERTIES
 /* #define USE_UNICODE_CASE_FOLD_TURKISH_AZERI */
 /* #define USE_UNICODE_ALL_LINE_TERMINATORS */  /* see Unicode.org UTS #18 */
+#define USE_CASE_MAP_API
 
 
 #define ONIG_ENCODING_INIT_DEFAULT           ONIG_ENCODING_ASCII
diff --git a/regerror.c b/regerror.c
index 8667084d41c931..e772feee81914a 100644
--- a/regerror.c
+++ b/regerror.c
@@ -3,7 +3,7 @@
 **********************************************************************/
 /*-
  * Copyright (c) 2002-2007  K.Kosako  <sndgk393 AT ybb DOT ne DOT jp>
- * Copyright (c) 2011-2016  K.Takata  <kentkt AT csc DOT jp>
+ * Copyright (c) 2011-2019  K.Takata  <kentkt AT csc DOT jp>
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -63,14 +63,18 @@ onig_error_code_to_format(OnigPosition code)
     p = "parse depth limit over"; break;
   case ONIGERR_DEFAULT_ENCODING_IS_NOT_SET:
     p = "default multibyte-encoding is not set"; break;
+#if 0
   case ONIGERR_SPECIFIED_ENCODING_CANT_CONVERT_TO_WIDE_CHAR:
     p = "can't convert to wide-char on specified multibyte-encoding"; break;
+#endif
   case ONIGERR_INVALID_ARGUMENT:
     p = "invalid argument"; break;
   case ONIGERR_END_PATTERN_AT_LEFT_BRACE:
     p = "end pattern at left brace"; break;
+#if 0
   case ONIGERR_END_PATTERN_AT_LEFT_BRACKET:
     p = "end pattern at left bracket"; break;
+#endif
   case ONIGERR_EMPTY_CHAR_CLASS:
     p = "empty char-class"; break;
   case ONIGERR_PREMATURE_END_OF_CHAR_CLASS:
@@ -87,16 +91,20 @@ onig_error_code_to_format(OnigPosition code)
     p = "invalid control-code syntax"; break;
   case ONIGERR_CHAR_CLASS_VALUE_AT_END_OF_RANGE:
     p = "char-class value at end of range"; break;
+#if 0
   case ONIGERR_CHAR_CLASS_VALUE_AT_START_OF_RANGE:
     p = "char-class value at start of range"; break;
+#endif
   case ONIGERR_UNMATCHED_RANGE_SPECIFIER_IN_CHAR_CLASS:
     p = "unmatched range specifier in char-class"; break;
   case ONIGERR_TARGET_OF_REPEAT_OPERATOR_NOT_SPECIFIED:
     p = "target of repeat operator is not specified"; break;
   case ONIGERR_TARGET_OF_REPEAT_OPERATOR_INVALID:
     p = "target of repeat operator is invalid"; break;
+#if 0
   case ONIGERR_NESTED_REPEAT_OPERATOR:
     p = "nested repeat operator"; break;
+#endif
   case ONIGERR_UNMATCHED_CLOSE_PARENTHESIS:
     p = "unmatched close parenthesis"; break;
   case ONIGERR_END_PATTERN_WITH_UNMATCHED_PARENTHESIS:
@@ -121,14 +129,18 @@ onig_error_code_to_format(OnigPosition code)
     p = "upper is smaller than lower in repeat range"; break;
   case ONIGERR_EMPTY_RANGE_IN_CHAR_CLASS:
     p = "empty range in char class"; break;
+#if 0
   case ONIGERR_MISMATCH_CODE_LENGTH_IN_CLASS_RANGE:
     p = "mismatch multibyte code length in char-class range"; break;
+#endif
   case ONIGERR_TOO_MANY_MULTI_BYTE_RANGES:
     p = "too many multibyte code ranges are specified"; break;
   case ONIGERR_TOO_SHORT_MULTI_BYTE_STRING:
     p = "too short multibyte code string"; break;
+#if 0
   case ONIGERR_TOO_BIG_BACKREF_NUMBER:
     p = "too big backref number"; break;
+#endif
   case ONIGERR_INVALID_BACKREF:
 #ifdef USE_NAMED_GROUP
     p = "invalid backref number/name"; break;
@@ -161,8 +173,10 @@ onig_error_code_to_format(OnigPosition code)
     p = "multiplex definition name <%n> call"; break;
   case ONIGERR_NEVER_ENDING_RECURSION:
     p = "never ending recursion"; break;
+#ifdef USE_CAPTURE_HISTORY
   case ONIGERR_GROUP_NUMBER_OVER_FOR_CAPTURE_HISTORY:
     p = "group number is too big for capture history"; break;
+#endif
   case ONIGERR_INVALID_CHAR_PROPERTY_NAME:
     p = "invalid character property name {%n}"; break;
   case ONIGERR_TOO_MANY_CAPTURE_GROUPS:
diff --git a/regexec.c b/regexec.c
index eec3e236631805..3210c7cc1b5603 100644
--- a/regexec.c
+++ b/regexec.c
@@ -2,8 +2,8 @@
   regexec.c -  Onigmo (Oniguruma-mod) (regular expression library)
 **********************************************************************/
 /*-
- * Copyright (c) 2002-2008  K.Kosako  <sndgk393 AT ybb DOT ne DOT jp>
- * Copyright (c) 2011-2016  K.Takata  <kentkt AT csc DOT jp>
+ * Copyright (c) 2002-2018  K.Kosako  <sndgk393 AT ybb DOT ne DOT jp>
+ * Copyright (c) 2011-2019  K.Takata  <kentkt AT csc DOT jp>
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -4401,39 +4401,19 @@ bm_search_notrev(regex_t* reg, const UChar* target, const UChar* target_end,
 
   s = text;
 
-  if (IS_NULL(reg->int_map)) {
-    while (s < end) {
-      p = se = s + tlen1;
-      t = tail;
-      while (*p == *t) {
-        if (t == target) return (UChar* )s;
-        p--; t--;
-      }
-      if (s + 1 >= end) break;
-      skip = reg->map[se[1]];
-      t = s;
-      do {
-        s += enclen(enc, s, end);
-      } while ((s - t) < skip && s < end);
-    }
-  }
-  else {
-# if OPT_EXACT_MAXLEN >= ONIG_CHAR_TABLE_SIZE
-    while (s < end) {
-      p = se = s + tlen1;
-      t = tail;
-      while (*p == *t) {
-        if (t == target) return (UChar* )s;
-        p--; t--;
-      }
-      if (s + 1 >= end) break;
-      skip = reg->int_map[se[1]];
-      t = s;
-      do {
-        s += enclen(enc, s, end);
-      } while ((s - t) < skip && s < end);
+  while (s < end) {
+    p = se = s + tlen1;
+    t = tail;
+    while (*p == *t) {
+      if (t == target) return (UChar* )s;
+      p--; t--;
     }
-# endif
+    if (s + 1 >= end) break;
+    skip = reg->map[se[1]];
+    t = s;
+    do {
+      s += enclen(enc, s, end);
+    } while ((s - t) < skip && s < end);
   }
 
   return (UChar* )NULL;
@@ -4460,32 +4440,17 @@ bm_search(regex_t* reg, const UChar* target, const UChar* target_end,
     end = text_end;
 
   s = text + tlen1;
-  if (IS_NULL(reg->int_map)) {
-    while (s < end) {
-      p = s;
-      t = tail;
-      while (*p == *t) {
-        if (t == target) return (UChar* )p;
-        p--; t--;
-      }
-      if (s + 1 >= end) break;
-      s += reg->map[s[1]];
-    }
-  }
-  else { /* see int_map[] */
-# if OPT_EXACT_MAXLEN >= ONIG_CHAR_TABLE_SIZE
-    while (s < end) {
-      p = s;
-      t = tail;
-      while (*p == *t) {
-        if (t == target) return (UChar* )p;
-        p--; t--;
-      }
-      if (s + 1 >= end) break;
-      s += reg->int_map[s[1]];
+  while (s < end) {
+    p = s;
+    t = tail;
+    while (*p == *t) {
+      if (t == target) return (UChar* )p;
+      p--; t--;
     }
-# endif
+    if (s + 1 >= end) break;
+    s += reg->map[s[1]];
   }
+
   return (UChar* )NULL;
 }
 
@@ -4514,35 +4479,17 @@ bm_search_notrev_ic(regex_t* reg, const UChar* target, const UChar* target_end,
 
   s = text;
 
-  if (IS_NULL(reg->int_map)) {
-    while (s < end) {
-      se = s + tlen1;
-      if (str_lower_case_match(enc, case_fold_flag, target, target_end,
-                               s, se + 1))
-        return (UChar* )s;
-      if (s + 1 >= end) break;
-      skip = reg->map[se[1]];
-      t = s;
-      do {
-        s += enclen(enc, s, end);
-      } while ((s - t) < skip && s < end);
-    }
-  }
-  else {
-# if OPT_EXACT_MAXLEN >= ONIG_CHAR_TABLE_SIZE
-    while (s < end) {
-      se = s + tlen1;
-      if (str_lower_case_match(enc, case_fold_flag, target, target_end,
-                               s, se + 1))
-        return (UChar* )s;
-      if (s + 1 >= end) break;
-      skip = reg->int_map[se[1]];
-      t = s;
-      do {
-        s += enclen(enc, s, end);
-      } while ((s - t) < skip && s < end);
-    }
-# endif
+  while (s < end) {
+    se = s + tlen1;
+    if (str_lower_case_match(enc, case_fold_flag, target, target_end,
+                             s, se + 1))
+      return (UChar* )s;
+    if (s + 1 >= end) break;
+    skip = reg->map[se[1]];
+    t = s;
+    do {
+      s += enclen(enc, s, end);
+    } while ((s - t) < skip && s < end);
   }
 
   return (UChar* )NULL;
@@ -4571,82 +4518,17 @@ bm_search_ic(regex_t* reg, const UChar* target, const UChar* target_end,
     end = text_end;
 
   s = text + tlen1;
-  if (IS_NULL(reg->int_map)) {
-    while (s < end) {
-      p = s - tlen1;
-      if (str_lower_case_match(enc, case_fold_flag, target, target_end,
-                               p, s + 1))
-        return (UChar* )p;
-      if (s + 1 >= end) break;
-      s += reg->map[s[1]];
-    }
-  }
-  else { /* see int_map[] */
-# if OPT_EXACT_MAXLEN >= ONIG_CHAR_TABLE_SIZE
-    while (s < end) {
-      p = s - tlen1;
-      if (str_lower_case_match(enc, case_fold_flag, target, target_end,
-                               p, s + 1))
-        return (UChar* )p;
-      if (s + 1 >= end) break;
-      s += reg->int_map[s[1]];
-    }
-# endif
-  }
-  return (UChar* )NULL;
-}
-
-#ifdef USE_INT_MAP_BACKWARD
-static int
-set_bm_backward_skip(UChar* s, UChar* end, OnigEncoding enc ARG_UNUSED,
-                     int** skip)
-{
-  int i, len;
-
-  if (IS_NULL(*skip)) {
-    *skip = (int* )xmalloc(sizeof(int) * ONIG_CHAR_TABLE_SIZE);
-    if (IS_NULL(*skip)) return ONIGERR_MEMORY;
-  }
-
-  len = (int )(end - s);
-  for (i = 0; i < ONIG_CHAR_TABLE_SIZE; i++)
-    (*skip)[i] = len;
-
-  for (i = len - 1; i > 0; i--)
-    (*skip)[s[i]] = i;
-
-  return 0;
-}
-
-static UChar*
-bm_search_backward(regex_t* reg, const UChar* target, const UChar* target_end,
-                   const UChar* text, const UChar* adjust_text,
-                   const UChar* text_end, const UChar* text_start)
-{
-  const UChar *s, *t, *p;
-
-  s = text_end - (target_end - target);
-  if (text_start < s)
-    s = text_start;
-  else
-    s = ONIGENC_LEFT_ADJUST_CHAR_HEAD(reg->enc, adjust_text, s, text_end);
-
-  while (s >= text) {
-    p = s;
-    t = target;
-    while (t < target_end && *p == *t) {
-      p++; t++;
-    }
-    if (t == target_end)
-      return (UChar* )s;
-
-    s -= reg->int_map_backward[*s];
-    s = ONIGENC_LEFT_ADJUST_CHAR_HEAD(reg->enc, adjust_text, s, text_end);
+  while (s < end) {
+    p = s - tlen1;
+    if (str_lower_case_match(enc, case_fold_flag, target, target_end,
+                             p, s + 1))
+      return (UChar* )p;
+    if (s + 1 >= end) break;
+    s += reg->map[s[1]];
   }
 
   return (UChar* )NULL;
 }
-#endif
 
 static UChar*
 map_search(OnigEncoding enc, UChar map[],
@@ -4894,21 +4776,7 @@ backward_search_range(regex_t* reg, const UChar* str, const UChar* end,
 
   case ONIG_OPTIMIZE_EXACT_BM:
   case ONIG_OPTIMIZE_EXACT_BM_NOT_REV:
-#ifdef USE_INT_MAP_BACKWARD
-    if (IS_NULL(reg->int_map_backward)) {
-      int r;
-      if (s - range < BM_BACKWARD_SEARCH_LENGTH_THRESHOLD)
-        goto exact_method;
-
-      r = set_bm_backward_skip(reg->exact, reg->exact_end, reg->enc,
-                               &(reg->int_map_backward));
-      if (r) return r;
-    }
-    p = bm_search_backward(reg, reg->exact, reg->exact_end, range, adjrange,
-                           end, p);
-#else
     goto exact_method;
-#endif
     break;
 
   case ONIG_OPTIMIZE_MAP:
diff --git a/regint.h b/regint.h
index 9d69e2d25e51a8..3f4aa919e5046f 100644
--- a/regint.h
+++ b/regint.h
@@ -5,7 +5,7 @@
 **********************************************************************/
 /*-
  * Copyright (c) 2002-2013  K.Kosako  <sndgk393 AT ybb DOT ne DOT jp>
- * Copyright (c) 2011-2016  K.Takata  <kentkt AT csc DOT jp>
+ * Copyright (c) 2011-2019  K.Takata  <kentkt AT csc DOT jp>
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -91,7 +91,7 @@
 #define DEFAULT_MATCH_STACK_LIMIT_SIZE              0 /* unlimited */
 #define DEFAULT_PARSE_DEPTH_LIMIT                4096
 
-#define OPT_EXACT_MAXLEN   24
+#define OPT_EXACT_MAXLEN   24	/* This must be smaller than ONIG_CHAR_TABLE_SIZE. */
 
 /* check config */
 #if defined(USE_PERL_SUBEXP_CALL) || defined(USE_CAPITAL_P_NAMED_GROUP)
diff --git a/regparse.c b/regparse.c
index 418bd3814076d9..123b3015a5a936 100644
--- a/regparse.c
+++ b/regparse.c
@@ -3,7 +3,7 @@
 **********************************************************************/
 /*-
  * Copyright (c) 2002-2008  K.Kosako  <sndgk393 AT ybb DOT ne DOT jp>
- * Copyright (c) 2011-2016  K.Takata  <kentkt AT csc DOT jp>
+ * Copyright (c) 2011-2019  K.Takata  <kentkt AT csc DOT jp>
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -4043,7 +4043,11 @@ fetch_token(OnigToken* tok, UChar** src, UChar* end, ScanEnv* env)
 
           if (c == 'R' || c == '0') {
             PINC;   /* skip 'R' / '0' */
-            if (!PPEEK_IS(')')) return ONIGERR_INVALID_GROUP_NAME;
+            if (!PPEEK_IS(')')) {
+              r = ONIGERR_INVALID_GROUP_NAME;
+              onig_scan_env_set_error_string(env, r, p - 1, p + 1);
+              return r;
+            }
             PINC;   /* skip ')' */
             name_end = name = p;
             gnum = 0;
@@ -6309,11 +6313,14 @@ parse_exp(Node** np, OnigToken* tok, int term,
   int r, len, group = 0;
   Node* qn;
   Node** targetp;
+  unsigned int parse_depth;
 
   *np = NULL;
   if (tok->type == (enum TokenSyms )term)
     goto end_of_token;
 
+  parse_depth = env->parse_depth;
+
   switch (tok->type) {
   case TK_ALT:
   case TK_EOT:
@@ -6624,6 +6631,10 @@ parse_exp(Node** np, OnigToken* tok, int term,
       if (is_invalid_quantifier_target(*targetp))
         return ONIGERR_TARGET_OF_REPEAT_OPERATOR_INVALID;
 
+      parse_depth++;
+      if (parse_depth > ParseDepthLimit)
+	return ONIGERR_PARSE_DEPTH_LIMIT_OVER;
+
       qn = node_new_quantifier(tok->u.repeat.lower, tok->u.repeat.upper,
                                (r == TK_INTERVAL ? 1 : 0));
       CHECK_NULL_RETURN_MEMERR(qn);
diff --git a/regparse.h b/regparse.h
index dd35d485255bad..65da835a55aca1 100644
--- a/regparse.h
+++ b/regparse.h
@@ -5,7 +5,7 @@
 **********************************************************************/
 /*-
  * Copyright (c) 2002-2007  K.Kosako  <sndgk393 AT ybb DOT ne DOT jp>
- * Copyright (c) 2011-2016  K.Takata  <kentkt AT csc DOT jp>
+ * Copyright (c) 2011-2019  K.Takata  <kentkt AT csc DOT jp>
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
diff --git a/sprintf.c b/sprintf.c
index cb266a98416e33..de88a9f4b35a20 100644
--- a/sprintf.c
+++ b/sprintf.c
@@ -441,7 +441,7 @@ rb_str_format(int argc, const VALUE *argv, VALUE fmt)
                 VALUE val = GETARG();
                 VALUE tmp;
                 unsigned int c;
-                int n;
+                int n, encidx;
 
                 tmp = rb_check_string_type(val);
                 if (!NIL_P(tmp)) {
@@ -451,11 +451,13 @@ rb_str_format(int argc, const VALUE *argv, VALUE fmt)
                     goto format_s1;
                 }
                 n = NUM2INT(val);
-                if (n >= 0) n = rb_enc_codelen((c = n), enc);
+                if (n >= 0) {
+                    n = rb_enc_codelen((c = n), enc);
+                    encidx = rb_ascii8bit_appendable_encoding_index(enc, c);
+                }
                 if (n <= 0) {
                     rb_raise(rb_eArgError, "invalid character");
                 }
-                int encidx = rb_ascii8bit_appendable_encoding_index(enc, c);
                 if (encidx >= 0 && encidx != rb_enc_to_index(enc)) {
                     /* special case */
                     rb_enc_associate_index(result, encidx);
diff --git a/tool/sync_default_gems.rb b/tool/sync_default_gems.rb
index 6945c6cdce52a6..b37c75e704bb4a 100755
--- a/tool/sync_default_gems.rb
+++ b/tool/sync_default_gems.rb
@@ -66,6 +66,19 @@ def lib((upstream, branch), gemspec_in_subdir: false)
     "lib/unicode_normalize",    # not to match with "lib/un"
   ]
   REPOSITORIES = {
+    Onigmo: repo("k-takata/Onigmo", [
+      ["regcomp.c", "regcomp.c"],
+      ["regenc.c", "regenc.c"],
+      ["regenc.h", "regenc.h"],
+      ["regerror.c", "regerror.c"],
+      ["regexec.c", "regexec.c"],
+      ["regint.h", "regint.h"],
+      ["regparse.c", "regparse.c"],
+      ["regparse.h", "regparse.h"],
+      ["regsyntax.c", "regsyntax.c"],
+      ["onigmo.h", "include/ruby/onigmo.h"],
+      ["enc", "enc"],
+    ]),
     "io-console": repo("ruby/io-console", [
       ["ext/io/console", "ext/io/console"],
       ["test/io/console", "test/io/console"],
diff --git a/zjit/bindgen/src/main.rs b/zjit/bindgen/src/main.rs
index 798a460c1980ac..794293d1d321c7 100644
--- a/zjit/bindgen/src/main.rs
+++ b/zjit/bindgen/src/main.rs
@@ -413,8 +413,6 @@ fn main() {
         .allowlist_function("rb_FL_TEST_RAW")
         .allowlist_function("rb_RB_TYPE_P")
         .allowlist_function("rb_BASIC_OP_UNREDEFINED_P")
-        .allowlist_function("rb_RSTRUCT_LEN")
-        .allowlist_function("rb_RSTRUCT_SET")
         .allowlist_function("rb_vm_ci_argc")
         .allowlist_function("rb_vm_ci_mid")
         .allowlist_function("rb_vm_ci_flag")
diff --git a/zjit/src/cruby.rs b/zjit/src/cruby.rs
index 57a3bee7e01d8c..51faaab9c24658 100644
--- a/zjit/src/cruby.rs
+++ b/zjit/src/cruby.rs
@@ -198,7 +198,6 @@ pub use rb_FL_TEST as FL_TEST;
 pub use rb_FL_TEST_RAW as FL_TEST_RAW;
 pub use rb_RB_TYPE_P as RB_TYPE_P;
 pub use rb_BASIC_OP_UNREDEFINED_P as BASIC_OP_UNREDEFINED_P;
-pub use rb_RSTRUCT_LEN as RSTRUCT_LEN;
 pub use rb_vm_ci_argc as vm_ci_argc;
 pub use rb_vm_ci_mid as vm_ci_mid;
 pub use rb_vm_ci_flag as vm_ci_flag;
diff --git a/zjit/src/cruby_bindings.inc.rs b/zjit/src/cruby_bindings.inc.rs
index efb1559fb75512..5d4fed0c3ac18d 100644
--- a/zjit/src/cruby_bindings.inc.rs
+++ b/zjit/src/cruby_bindings.inc.rs
@@ -2153,7 +2153,6 @@ unsafe extern "C" {
     pub fn rb_FL_TEST(obj: VALUE, flags: VALUE) -> VALUE;
     pub fn rb_FL_TEST_RAW(obj: VALUE, flags: VALUE) -> VALUE;
     pub fn rb_RB_TYPE_P(obj: VALUE, t: ruby_value_type) -> bool;
-    pub fn rb_RSTRUCT_LEN(st: VALUE) -> ::std::os::raw::c_long;
     pub fn rb_get_call_data_ci(cd: *const rb_call_data) -> *const rb_callinfo;
     pub fn rb_BASIC_OP_UNREDEFINED_P(bop: ruby_basic_operators, klass: u32) -> bool;
     pub fn rb_RCLASS_ORIGIN(c: VALUE) -> VALUE;