diff --git a/src/mfast/coder/encoder/fast_encoder.cpp b/src/mfast/coder/encoder/fast_encoder.cpp
index 27257ac5..ca36ba86 100644
--- a/src/mfast/coder/encoder/fast_encoder.cpp
+++ b/src/mfast/coder/encoder/fast_encoder.cpp
@@ -124,6 +124,16 @@ inline void fast_encoder_impl::visit(group_cref cref, int) {
 
 inline void fast_encoder_impl::visit(sequence_cref cref, int) {
 
+  if (cref.instruction()->optional() && !cref.present()) {
+    if (cref.instruction()->length_instruction()->pmap_size() > 0)
+      this->current_->set_next_bit(false);
+    if (cref.instruction()->length_instruction()->field_operator() != operator_constant &&
+        cref.instruction()->length_instruction()->field_operator() != operator_default &&
+        cref.instruction()->length_instruction()->field_operator() != operator_copy)
+      strm_.encode_null();
+    return;
+  }
+
   value_storage storage;
 
   uint32_mref length_mref(nullptr, &storage,
diff --git a/src/mfast/coder/encoder_v2/fast_encoder_core.h b/src/mfast/coder/encoder_v2/fast_encoder_core.h
index 345627ae..b90d169d 100644
--- a/src/mfast/coder/encoder_v2/fast_encoder_core.h
+++ b/src/mfast/coder/encoder_v2/fast_encoder_core.h
@@ -259,6 +259,17 @@ inline void fast_encoder_core::encode_field(const T &ext_ref, group_type_tag) {
 template <typename T>
 inline void fast_encoder_core::encode_field(const T &ext_ref,
                                             sequence_type_tag) {
+
+  if (ext_ref.get().instruction()->optional() && !ext_ref.present()) {
+    if (T::length_type::has_pmap_type::value)
+      this->current_->set_next_bit(false);
+    if(!std::is_same<typename T::length_type::operator_category, constant_operator_tag>::value &&
+       !std::is_same<typename T::length_type::operator_category, copy_operator_tag>::value &&
+       !std::is_same<typename T::length_type::operator_category, default_operator_tag>::value)
+      strm_.encode_null();
+    return;
+  }
+
   value_storage storage;
 
   typename T::length_type length = ext_ref.get_length(storage);
diff --git a/src/mfast/ext_ref.h b/src/mfast/ext_ref.h
index 33edb1d6..60bf81aa 100644
--- a/src/mfast/ext_ref.h
+++ b/src/mfast/ext_ref.h
@@ -167,6 +167,8 @@ class ext_cref<sequence_cref, LengthExtRef, ElementExtRef> {
   }
   std::size_t size() const { return base_.size(); }
 
+  bool present() const { return base_.present(); }
+
 private:
   sequence_cref base_;
 };
diff --git a/tests/CMakeLists.txt b/tests/CMakeLists.txt
index fb9d29bc..4cd388e6 100644
--- a/tests/CMakeLists.txt
+++ b/tests/CMakeLists.txt
@@ -74,7 +74,7 @@ add_executable (mfast_test
                 aggregate_view_test.cpp
                 simple_coder_test.cpp
                 sequence_encoder_decoder_v2.cpp
-                sequence_encoder_decoder_v2.cpp
+                sequence_encoder_decoder.cpp
                 scp_reset_test.cpp
                 template_repo_base.cpp
                 message_pmap_test.cpp
diff --git a/tests/encoder_decoder_test.cpp b/tests/encoder_decoder_test.cpp
index 96271e48..768b663d 100644
--- a/tests/encoder_decoder_test.cpp
+++ b/tests/encoder_decoder_test.cpp
@@ -245,3 +245,38 @@ TEST_CASE("simple optional field with default value encoder/decoder","[optional_
         REQUIRE(test_case.decoding("\xD0\x86\x82",test_6.cref(),true));
     }
 }
+
+TEST_CASE("sequence optional with constant length encoder/decoder","[optional_sequence_with_constant_length_encoder_decoder]")
+{
+    fast_test_coding_case<simple12::templates_description> test_case;
+
+    SECTION("encode fields without sequence")
+    {
+        simple12::Test_7 test_7;
+        simple12::Test_7_mref test_7_mref = test_7.mref();
+        test_7_mref.set_field_7_1().as(1);
+        REQUIRE(test_case.encoding(test_7.cref(),"\xE0\x87\x82",true));
+        REQUIRE(test_case.decoding("\xE0\x87\x82",test_7.cref(),true));
+    }
+
+    SECTION("encode fields with sequence")
+    {
+        simple12::Test_7 test_7;
+        simple12::Test_7_mref test_7_mref = test_7.mref();
+        test_7_mref.set_field_7_1().as(1);
+
+        {
+            auto sequence_7_mref = test_7_mref.set_sequence_7();
+            sequence_7_mref.resize(1);
+
+            {
+                auto element_sequence = sequence_7_mref.front();
+                element_sequence.set_field_7_4().as(1);
+                element_sequence.set_field_7_5().as(1);
+            }
+        }
+
+        REQUIRE(test_case.encoding(test_7.cref(),"\xF0\x87\x82\xa0\x82\x82",true));
+        REQUIRE(test_case.decoding("\xF0\x87\x82\xa0\x82\x82",test_7.cref(),true));
+    }
+}
diff --git a/tests/encoder_decoder_test_v2.cpp b/tests/encoder_decoder_test_v2.cpp
index 4846e84a..0aabce9d 100644
--- a/tests/encoder_decoder_test_v2.cpp
+++ b/tests/encoder_decoder_test_v2.cpp
@@ -22,7 +22,7 @@ TEST_CASE("simple field and sequence optional encoder_v2/decoder_v2","[field_seq
         // 1 : Set Template Id.
         // 1 : Set Field field_1_1
         // 0 : XXX
-        REQUIRE(test_case.encoding(test_1.cref(),"\xE0\x81\x82\x81",true));
+        REQUIRE(test_case.encoding(test_1.cref(),"\xE0\x81\x82\x80",true));
         REQUIRE(test_case.decoding("\xE0\x81\x82\x80",test_1.cref(),true));
     }
 
@@ -246,3 +246,38 @@ TEST_CASE("simple optional field with default value encoder_v2/decoder_v2","[opt
         REQUIRE(test_case.decoding("\xD0\x86\x82",test_6.cref(),true));
     }
 }
+
+TEST_CASE("sequence optional with constant length encoder_v2/decoder_v2","[optional_sequence_with_constant_length_encoder_v2/decoder_v2]")
+{
+    fast_test_coding_case_v2<simple12::templates_description> test_case;
+
+    SECTION("encode fields without sequence")
+    {
+        simple12::Test_7 test_7;
+        simple12::Test_7_mref test_7_mref = test_7.mref();
+        test_7_mref.set_field_7_1().as(1);
+        REQUIRE(test_case.encoding(test_7.cref(),"\xE0\x87\x82",true));
+        REQUIRE(test_case.decoding("\xE0\x87\x82",test_7.cref(),true));
+    }
+
+    SECTION("encode fields with sequence")
+    {
+        simple12::Test_7 test_7;
+        simple12::Test_7_mref test_7_mref = test_7.mref();
+        test_7_mref.set_field_7_1().as(1);
+
+        {
+            auto sequence_7_mref = test_7_mref.set_sequence_7();
+            sequence_7_mref.resize(1);
+
+            {
+                auto element_sequence = sequence_7_mref.front();
+                element_sequence.set_field_7_4().as(1);
+                element_sequence.set_field_7_5().as(1);
+            }
+        }
+
+        REQUIRE(test_case.encoding(test_7.cref(),"\xF0\x87\x82\xa0\x82\x82",true));
+        REQUIRE(test_case.decoding("\xF0\x87\x82\xa0\x82\x82",test_7.cref(),true));
+    }
+}
diff --git a/tests/group_encoder_decoder.cpp b/tests/group_encoder_decoder.cpp
index 00d19977..029f5d9f 100644
--- a/tests/group_encoder_decoder.cpp
+++ b/tests/group_encoder_decoder.cpp
@@ -39,4 +39,53 @@ TEST_CASE("field with group encoder/decoder","[field_without_group_encoder_decod
     REQUIRE(test_case.decoding("\xE0\x81\x9F\xA8\x80\x8B",test_1.cref(),true));
 }
 
+TEST_CASE("optional group encoder/decoder","[optional_group_encoder_decoder]")
+{
+    fast_test_coding_case<simple13::templates_description> test_case;
+
+    SECTION("No group")
+    {
+        simple13::Test_4 test_4;
+
+        REQUIRE(test_case.encoding(test_4.cref(),"\xC0\x84",true));
+        REQUIRE(test_case.decoding("\xC0\x84",test_4.cref(),true));
+    }
+
+    SECTION("With group")
+    {
+        simple13::Test_4 test_4;
+        simple13::Test_4_mref test_4_mref = test_4.mref();
+
+        // set group
+        {
+            auto group_1 = test_4_mref.set_group_4_1();
+            auto sequence_4_mref = group_1.set_sequence_4();
+            sequence_4_mref.resize(1);
+            auto element_sequence = sequence_4_mref.front();
+            element_sequence.set_field_4_3().as(1);
+        }
 
+        REQUIRE(test_case.encoding(test_4.cref(),"\xE0\x84\x80\xC0\x81",true));
+        REQUIRE(test_case.decoding("\xE0\x84\x80\xC0\x81",test_4.cref(),true));
+    }
+
+    SECTION("With group sequence and field")
+    {
+        simple13::Test_4 test_4;
+        simple13::Test_4_mref test_4_mref = test_4.mref();
+
+        // set group
+        {
+            auto group_1 = test_4_mref.set_group_4_1();
+            auto sequence_4_mref = group_1.set_sequence_4();
+            sequence_4_mref.resize(1);
+            auto element_sequence = sequence_4_mref.front();
+            element_sequence.set_field_4_3().as(1);
+
+            group_1.set_field_4_4().as(10);
+        }
+
+        REQUIRE(test_case.encoding(test_4.cref(),"\xE0\x84\xC0\xC0\x81\x8B",true));
+        REQUIRE(test_case.decoding("\xE0\x84\xC0\xC0\x81\x8B",test_4.cref(),true));
+    }
+}
diff --git a/tests/group_encoder_decoder_v2.cpp b/tests/group_encoder_decoder_v2.cpp
index 1c5a624e..bc3c8442 100644
--- a/tests/group_encoder_decoder_v2.cpp
+++ b/tests/group_encoder_decoder_v2.cpp
@@ -39,4 +39,53 @@ TEST_CASE("field with group encoder_v2/decoder_v2","[field_without_group_encoder
     REQUIRE(test_case.decoding("\xE0\x81\x9F\xA8\x80\x8B",test_1.cref(),true));
 }
 
+TEST_CASE("optional group encoder_v2/decoder_v2","[optional_group_encoder_v2_decoder_v2]")
+{
+    fast_test_coding_case_v2<simple13::templates_description> test_case;
+
+    SECTION("No group")
+    {
+        simple13::Test_4 test_4;
+
+        REQUIRE(test_case.encoding(test_4.cref(),"\xC0\x84",true));
+        REQUIRE(test_case.decoding("\xC0\x84",test_4.cref(),true));
+    }
+
+    SECTION("With group")
+    {
+        simple13::Test_4 test_4;
+        simple13::Test_4_mref test_4_mref = test_4.mref();
+
+        // set group
+        {
+            auto group_1 = test_4_mref.set_group_4_1();
+            auto sequence_4_mref = group_1.set_sequence_4();
+            sequence_4_mref.resize(1);
+            auto element_sequence = sequence_4_mref.front();
+            element_sequence.set_field_4_3().as(1);
+        }
 
+        REQUIRE(test_case.encoding(test_4.cref(),"\xE0\x84\x80\xC0\x81",true));
+        REQUIRE(test_case.decoding("\xE0\x84\x80\xC0\x81",test_4.cref(),true));
+    }
+
+    SECTION("With group sequence and field")
+    {
+        simple13::Test_4 test_4;
+        simple13::Test_4_mref test_4_mref = test_4.mref();
+
+        // set group
+        {
+            auto group_1 = test_4_mref.set_group_4_1();
+            auto sequence_4_mref = group_1.set_sequence_4();
+            sequence_4_mref.resize(1);
+            auto element_sequence = sequence_4_mref.front();
+            element_sequence.set_field_4_3().as(1);
+
+            group_1.set_field_4_4().as(10);
+        }
+
+        REQUIRE(test_case.encoding(test_4.cref(),"\xE0\x84\xC0\xC0\x81\x8B",true));
+        REQUIRE(test_case.decoding("\xE0\x84\xC0\xC0\x81\x8B",test_4.cref(),true));
+    }
+}
diff --git a/tests/sequence_encoder_decoder.cpp b/tests/sequence_encoder_decoder.cpp
index 59bd9d29..e2d1fb8c 100644
--- a/tests/sequence_encoder_decoder.cpp
+++ b/tests/sequence_encoder_decoder.cpp
@@ -130,4 +130,110 @@ TEST_CASE("sequence optional none operator by length encoder/decoder","[sequence
     REQUIRE(test_case.decoding("\xC0\x84\x82\xC0\xB3\x8B",test_4.cref(),true));
 }
 
+TEST_CASE("sequence inside sequence encoder/decoder","[sequence_inside_sequence_encoder_decoder]")
+{
+    fast_test_coding_case<simple14::templates_description> test_case;
+
+    SECTION("outside sequence")
+    {
+        simple14::Test_5 test_5;
+        simple14::Test_5_mref test_5_mref = test_5.mref();
+
+        test_5_mref.set_field_5_2().as(1);
+
+        auto sequence_5_1_mref = test_5_mref.set_sequence_5_1();
+        sequence_5_1_mref.resize(1);
+
+        {
+            auto element_sequence = sequence_5_1_mref.front();
+            element_sequence.set_field_5_4().as(50);
+        }
+
+        REQUIRE(test_case.encoding(test_5.cref(),"\xD0\x85\x81\x81\xC0\xB3",true));
+        REQUIRE(test_case.decoding("\xD0\x85\x81\x81\xC0\xB3",test_5.cref(),true));
+    }
+
+    SECTION("inside sequence")
+    {
+        simple14::Test_5 test_5;
+        simple14::Test_5_mref test_5_mref = test_5.mref();
+
+        test_5_mref.set_field_5_2().as(1);
+
+        auto sequence_5_1_mref = test_5_mref.set_sequence_5_1();
+        sequence_5_1_mref.resize(1);
+
+        {
+            auto element_sequence = sequence_5_1_mref.front();
+            element_sequence.set_field_5_4().as(50);
+
+            auto sequence_5_2_mref = element_sequence.set_sequence_5_2();
+            sequence_5_2_mref.resize(1);
+
+            {
+                auto element_sequence_inside = sequence_5_2_mref.front();
+                element_sequence_inside.set_field_5_6().as(50);
+            }
+        }
 
+        REQUIRE(test_case.encoding(test_5.cref(),"\xD0\x85\x81\x81\xE0\xB3\x82\xB2",true));
+        REQUIRE(test_case.decoding("\xD0\x85\x81\x81\xE0\xB3\x82\xB2",test_5.cref(),true));
+    }
+}
+
+TEST_CASE("group sequence inside sequence encoder/decoder","[group_sequence_inside_sequence_encoder_decoder]")
+{
+    fast_test_coding_case<simple14::templates_description> test_case;
+
+    SECTION("outside sequence")
+    {
+        simple14::Test_6 test_6;
+        simple14::Test_6_mref test_6_mref = test_6.mref();
+
+        // set group
+        {
+            auto group_6 = test_6_mref.set_group_6();
+            auto sequence_6_1_mref = group_6.set_sequence_6_1();
+            sequence_6_1_mref.resize(1);
+
+            //set sequence
+            {
+                auto element_sequence = sequence_6_1_mref.front();
+                element_sequence.set_field_6_3().as(50);
+            }
+        }
+
+        REQUIRE(test_case.encoding(test_6.cref(),"\xC0\x86\x81\xC0\xB2",true));
+        REQUIRE(test_case.decoding("\xC0\x86\x81\xC0\xB2",test_6.cref(),true));
+    }
+
+    SECTION("inside sequence")
+    {
+        simple14::Test_6 test_6;
+        simple14::Test_6_mref test_6_mref = test_6.mref();
+
+        // set group
+        {
+            auto group_6 = test_6_mref.set_group_6();
+            auto sequence_6_1_mref = group_6.set_sequence_6_1();
+            sequence_6_1_mref.resize(1);
+
+            //set sequence
+            {
+                auto element_sequence = sequence_6_1_mref.front();
+                element_sequence.set_field_6_3().as(50);
+
+                auto sequence_6_2_mref = element_sequence.set_sequence_6_2();
+                sequence_6_2_mref.resize(1);
+
+                {
+                    auto element_sequence_inside = sequence_6_2_mref.front();
+                    element_sequence_inside.set_field_6_6().as(50);
+                }
+            }
+        }
+
+        REQUIRE(test_case.encoding(test_6.cref(),"\xC0\x86\x81\xD0\xB2\x82\xB2",true));
+        REQUIRE(test_case.decoding("\xC0\x86\x81\xD0\xB2\x82\xB2",test_6.cref(),true));
+    }
+}
diff --git a/tests/sequence_encoder_decoder_v2.cpp b/tests/sequence_encoder_decoder_v2.cpp
index a7cc992f..bbf05cdd 100644
--- a/tests/sequence_encoder_decoder_v2.cpp
+++ b/tests/sequence_encoder_decoder_v2.cpp
@@ -131,3 +131,111 @@ TEST_CASE("sequence optional none operator by length encoder_V2/decoder_v2","[se
     REQUIRE(test_case.encoding(test_4.cref(),"\xC0\x84\x82\xC0\xB3\x8B",true));
     REQUIRE(test_case.decoding("\xC0\x84\x82\xC0\xB3\x8B",test_4.cref(),true));
 }
+
+TEST_CASE("sequence inside sequence encoder_V2/decoder_v2","[sequence_inside_sequence_encoder_v2_decoder_v2]")
+{
+    fast_test_coding_case_v2<simple14::templates_description> test_case;
+
+    SECTION("outside sequence")
+    {
+        simple14::Test_5 test_5;
+        simple14::Test_5_mref test_5_mref = test_5.mref();
+
+        test_5_mref.set_field_5_2().as(1);
+
+        auto sequence_5_1_mref = test_5_mref.set_sequence_5_1();
+        sequence_5_1_mref.resize(1);
+
+        {
+            auto element_sequence = sequence_5_1_mref.front();
+            element_sequence.set_field_5_4().as(50);
+        }
+
+        REQUIRE(test_case.encoding(test_5.cref(),"\xD0\x85\x81\x81\xC0\xB3",true));
+        REQUIRE(test_case.decoding("\xD0\x85\x81\x81\xC0\xB3",test_5.cref(),true));
+    }
+
+    SECTION("inside sequence")
+    {
+        simple14::Test_5 test_5;
+        simple14::Test_5_mref test_5_mref = test_5.mref();
+
+        test_5_mref.set_field_5_2().as(1);
+
+        auto sequence_5_1_mref = test_5_mref.set_sequence_5_1();
+        sequence_5_1_mref.resize(1);
+
+        {
+            auto element_sequence = sequence_5_1_mref.front();
+            element_sequence.set_field_5_4().as(50);
+
+            auto sequence_5_2_mref = element_sequence.set_sequence_5_2();
+            sequence_5_2_mref.resize(1);
+
+            {
+                auto element_sequence_inside = sequence_5_2_mref.front();
+                element_sequence_inside.set_field_5_6().as(50);
+            }
+        }
+
+        REQUIRE(test_case.encoding(test_5.cref(),"\xD0\x85\x81\x81\xE0\xB3\x82\xB2",true));
+        REQUIRE(test_case.decoding("\xD0\x85\x81\x81\xE0\xB3\x82\xB2",test_5.cref(),true));
+    }
+}
+
+TEST_CASE("group sequence inside sequence encoder_V2/decoder_v2","[group_sequence_inside_sequence_encoder_v2_decoder_v2]")
+{
+    fast_test_coding_case_v2<simple14::templates_description> test_case;
+
+    SECTION("outside sequence")
+    {
+        simple14::Test_6 test_6;
+        simple14::Test_6_mref test_6_mref = test_6.mref();
+
+        // set group
+        {
+            auto group_6 = test_6_mref.set_group_6();
+            auto sequence_6_1_mref = group_6.set_sequence_6_1();
+            sequence_6_1_mref.resize(1);
+
+            //set sequence
+            {
+                auto element_sequence = sequence_6_1_mref.front();
+                element_sequence.set_field_6_3().as(50);
+            }
+        }
+
+        REQUIRE(test_case.encoding(test_6.cref(),"\xC0\x86\x81\xC0\xB2",true));
+        REQUIRE(test_case.decoding("\xC0\x86\x81\xC0\xB2",test_6.cref(),true));
+    }
+
+    SECTION("inside sequence")
+    {
+        simple14::Test_6 test_6;
+        simple14::Test_6_mref test_6_mref = test_6.mref();
+
+        // set group
+        {
+            auto group_6 = test_6_mref.set_group_6();
+            auto sequence_6_1_mref = group_6.set_sequence_6_1();
+            sequence_6_1_mref.resize(1);
+
+            //set sequence
+            {
+                auto element_sequence = sequence_6_1_mref.front();
+                element_sequence.set_field_6_3().as(50);
+
+                auto sequence_6_2_mref = element_sequence.set_sequence_6_2();
+                sequence_6_2_mref.resize(1);
+
+                {
+                    auto element_sequence_inside = sequence_6_2_mref.front();
+                    element_sequence_inside.set_field_6_6().as(50);
+                }
+            }
+        }
+
+        REQUIRE(test_case.encoding(test_6.cref(),"\xC0\x86\x81\xD0\xB2\x82\xB2",true));
+        REQUIRE(test_case.decoding("\xC0\x86\x81\xD0\xB2\x82\xB2",test_6.cref(),true));
+    }
+}
diff --git a/tests/simple12.xml b/tests/simple12.xml
index 2465c03d..db69f6e7 100644
--- a/tests/simple12.xml
+++ b/tests/simple12.xml
@@ -3,8 +3,9 @@
     <template name="Test_1" id="1">
         <uInt32 name="field_1_1" id="11" presence="optional"><copy/></uInt32>
         <sequence name="sequence_1" presence="optional">
-            <uInt32 name="field_1_2" id="12" presence="optional"></uInt32>
-            <uInt32 name="field_1_3" id="13" presence="optional"></uInt32>
+            <length name="num_elements" id="12"/>
+            <uInt32 name="field_1_2" id="13" presence="optional"></uInt32>
+            <uInt32 name="field_1_3" id="14" presence="optional"></uInt32>
         </sequence>
     </template>
     <template name="Test_2" id="2">
@@ -14,8 +15,9 @@
     <template name="Test_3" id="3">
         <uInt32 name="field_3_1" id="31"><copy/></uInt32>
         <sequence name="sequence_3">
-            <uInt32 name="field_3_2" id="32"></uInt32>
-            <uInt32 name="field_3_3" id="33"></uInt32>
+            <length name="num_elements" id="32"/>
+            <uInt32 name="field_3_2" id="33"></uInt32>
+            <uInt32 name="field_3_3" id="34"></uInt32>
         </sequence>
     </template>
     <template name="Test_4" id="4">
@@ -26,10 +28,11 @@
         <uInt32 name="field_5_1" id="51" presence="optional"><copy/></uInt32>
         <group name="test_5_group" presence="optional">
             <sequence name="sequence_5">
-                <uInt32 name="field_5_2" id="52"></uInt32>
-                <uInt32 name="field_5_3" id="53"></uInt32>
+                <length name="num_elements" id="52"/>
+                <uInt32 name="field_5_2" id="53"></uInt32>
+                <uInt32 name="field_5_3" id="54"></uInt32>
             </sequence>
-            <uInt32 name="field_5_5" id="54" presence="optional"><copy/></uInt32>
+            <uInt32 name="field_5_5" id="55" presence="optional"><copy/></uInt32>
         </group>
     </template>
     <template name="Test_6" id="6">
@@ -43,4 +46,23 @@
             <default value="1"/>
         </uInt32>
     </template>
+    <template name="Test_7" id="7">
+        <uInt32 name="field_7_1" id="71" presence="optional">
+            <copy/>
+        </uInt32>
+        <sequence name="sequence_7" presence="optional">
+            <length name="num_elements" id="72">
+                <constant value="1"/>
+            </length>
+            <uInt32 name="field_7_3" id="73">
+                <default value="0"/>
+            </uInt32>
+            <uInt32 name="field_7_4" id="74" presence="optional">
+                <delta/>
+            </uInt32>
+            <uInt32 name="field_7_5" id="75" presence="optional">
+                <copy/>
+            </uInt32>
+        </sequence>
+    </template>
 </templates>
diff --git a/tests/simple13.xml b/tests/simple13.xml
index 8f155d5b..dc05e18f 100644
--- a/tests/simple13.xml
+++ b/tests/simple13.xml
@@ -29,4 +29,20 @@
             </group>
         </group>
     </template>
+    <template name="Test_4" id="4">
+        <group name="group_4_1" presence="optional">
+            <sequence name="sequence_4">
+                <length name="field_4_1" id="41">
+                    <constant value="1"/>
+                </length>
+                <uInt32 name="field_4_2" id="42">
+                    <constant value="0"/>
+                </uInt32>
+                <uInt32 name="field_4_3" id="43">
+                    <copy/>
+                </uInt32>
+            </sequence>
+            <uInt32 name="field_4_4" id="44" presence="optional"><copy/></uInt32>
+        </group>
+    </template>
 </templates>
diff --git a/tests/simple14.xml b/tests/simple14.xml
index 97390a38..e7f9b916 100644
--- a/tests/simple14.xml
+++ b/tests/simple14.xml
@@ -28,4 +28,30 @@
         </sequence>
         <uInt32 name="field_4_3" id="43" presence="optional"></uInt32>
     </template>
+    <template name="Test_5" id="5">
+        <uInt32 name="field_5_1" id="51" presence="optional"><copy/></uInt32>
+        <uInt32 name="field_5_2" id="52"><copy/></uInt32>
+        <sequence name="sequence_5_1">
+            <length name="field_5_3" id="53"></length>
+            <uInt32 name="field_5_4" id="54" presence="optional"><copy/></uInt32>
+            <sequence name="sequence_5_2" presence="optional">
+                <length name="field_5_5" id="55"><copy/></length>
+                <uInt32 name="field_5_6" id="56"/>
+            </sequence>
+        </sequence>
+    </template>
+    <template name="Test_6" id="6">
+        <uInt32 name="field_6_1" id="61" presence="optional"><copy/></uInt32>
+        <group name="group_6">
+            <sequence name="sequence_6_1">
+                <length name="field_6_2" id="62"></length>
+                <uInt32 name="field_6_3" id="63"><copy/></uInt32>
+                <uInt32 name="field_6_4" id="64" presence="optional"><copy/></uInt32>
+                <sequence name="sequence_6_2" presence="optional">
+                    <length name="field_6_5" id="65"><copy/></length>
+                    <uInt32 name="field_6_6" id="66"/>
+                </sequence>
+            </sequence>
+        </group>
+    </template>
 </templates>