diff --git a/prism/prism.c b/prism/prism.c
index 4465b4982e13b5..4ab1ca4594db98 100644
--- a/prism/prism.c
+++ b/prism/prism.c
@@ -13907,6 +13907,43 @@ update_parameter_state(pm_parser_t *parser, pm_token_t *token, pm_parameters_ord
     return true;
 }
 
+static inline void
+parse_parameters_handle_trailing_comma(
+    pm_parser_t *parser,
+    pm_parameters_node_t *params,
+    pm_parameters_order_t order,
+    bool in_block,
+    bool allows_trailing_comma
+) {
+    if (!allows_trailing_comma) {
+        pm_parser_err_previous(parser, PM_ERR_PARAMETER_WILD_LOOSE_COMMA);
+        return;
+    }
+
+    if (in_block) {
+        if (order >= PM_PARAMETERS_ORDER_NAMED) {
+            // foo do |bar,|; end
+            pm_node_t *param = UP(pm_implicit_rest_node_create(parser, &parser->previous));
+
+            if (params->rest == NULL) {
+                pm_parameters_node_rest_set(params, param);
+            } else {
+                pm_parser_err_node(parser, UP(param), PM_ERR_PARAMETER_SPLAT_MULTI);
+                pm_parameters_node_posts_append(params, UP(param));
+            }
+        } else {
+            // foo do |*bar,|; end
+            pm_parser_err_previous(parser, PM_ERR_PARAMETER_WILD_LOOSE_COMMA);
+        }
+    } else {
+        // https://bugs.ruby-lang.org/issues/19107
+        // Allow `def foo(bar,); end`, `def foo(*bar,); end`, etc. but not `def foo(...,); end`
+        if (parser->version < PM_OPTIONS_VERSION_CRUBY_4_1 || order == PM_PARAMETERS_ORDER_NOTHING_AFTER) {
+            pm_parser_err_previous(parser, PM_ERR_PARAMETER_WILD_LOOSE_COMMA);
+        }
+    }
+}
+
 /**
  * Parse a list of parameters on a method definition.
  */
@@ -14255,20 +14292,7 @@ parse_parameters(
             }
             default:
                 if (parser->previous.type == PM_TOKEN_COMMA) {
-                    if (allows_trailing_comma && order >= PM_PARAMETERS_ORDER_NAMED) {
-                        // If we get here, then we have a trailing comma in a
-                        // block parameter list.
-                        pm_node_t *param = UP(pm_implicit_rest_node_create(parser, &parser->previous));
-
-                        if (params->rest == NULL) {
-                            pm_parameters_node_rest_set(params, param);
-                        } else {
-                            pm_parser_err_node(parser, UP(param), PM_ERR_PARAMETER_SPLAT_MULTI);
-                            pm_parameters_node_posts_append(params, UP(param));
-                        }
-                    } else {
-                        pm_parser_err_previous(parser, PM_ERR_PARAMETER_WILD_LOOSE_COMMA);
-                    }
+                    parse_parameters_handle_trailing_comma(parser, params, order, in_block, allows_trailing_comma);
                 }
 
                 parsing = false;
@@ -15933,6 +15957,19 @@ parse_heredoc_dedent_string(pm_string_t *string, size_t common_whitespace) {
     string->length = dest_length;
 }
 
+/**
+ * If we end up trimming all of the whitespace from a node and it isn't
+ * part of a line continuation, then we'll drop it from the list entirely.
+ */
+static inline bool
+heredoc_dedent_discard_string_node(pm_parser_t *parser, pm_string_node_t *string_node) {
+    if (string_node->unescaped.length == 0) {
+        const uint8_t *cursor = parser->start + PM_LOCATION_START(&string_node->content_loc);
+        return pm_memchr(cursor, '\\', string_node->content_loc.length, parser->encoding_changed, parser->encoding) == NULL;
+    }
+    return false;
+}
+
 /**
  * Take a heredoc node that is indented by a ~ and trim the leading whitespace.
  */
@@ -15943,8 +15980,7 @@ parse_heredoc_dedent(pm_parser_t *parser, pm_node_list_t *nodes, size_t common_w
     bool dedent_next = true;
 
     // Iterate over all nodes, and trim whitespace accordingly. We're going to
-    // keep around two indices: a read and a write. If we end up trimming all of
-    // the whitespace from a node, then we'll drop it from the list entirely.
+    // keep around two indices: a read and a write.
     size_t write_index = 0;
 
     pm_node_t *node;
@@ -15963,7 +15999,7 @@ parse_heredoc_dedent(pm_parser_t *parser, pm_node_list_t *nodes, size_t common_w
             parse_heredoc_dedent_string(&string_node->unescaped, common_whitespace);
         }
 
-        if (string_node->unescaped.length == 0) {
+        if (heredoc_dedent_discard_string_node(parser, string_node)) {
             pm_node_destroy(parser, node);
         } else {
             nodes->nodes[write_index++] = node;
@@ -18865,7 +18901,9 @@ parse_expression_prefix(pm_parser_t *parser, pm_binding_power_t binding_power, b
                     if (match1(parser, PM_TOKEN_PARENTHESIS_RIGHT)) {
                         params = NULL;
                     } else {
-                        params = parse_parameters(parser, PM_BINDING_POWER_DEFINED, true, false, true, true, false, (uint16_t) (depth + 1));
+                        // https://bugs.ruby-lang.org/issues/19107
+                        bool allow_trailing_comma = parser->version >= PM_OPTIONS_VERSION_CRUBY_4_1;
+                        params = parse_parameters(parser, PM_BINDING_POWER_DEFINED, true, allow_trailing_comma, true, true, false, (uint16_t) (depth + 1));
                     }
 
                     lex_state_set(parser, PM_LEX_STATE_BEG);
diff --git a/prism/templates/template.rb b/prism/templates/template.rb
index 65e6ed038168d9..18da0647a007bd 100755
--- a/prism/templates/template.rb
+++ b/prism/templates/template.rb
@@ -724,9 +724,9 @@ def locals
       "javascript/src/deserialize.js",
       "javascript/src/nodes.js",
       "javascript/src/visitor.js",
-      "java/org/prism/Loader.java",
-      "java/org/prism/Nodes.java",
-      "java/org/prism/AbstractNodeVisitor.java",
+      "java/org/ruby_lang/prism/Loader.java",
+      "java/org/ruby_lang/prism/Nodes.java",
+      "java/org/ruby_lang/prism/AbstractNodeVisitor.java",
       "lib/prism/compiler.rb",
       "lib/prism/dispatcher.rb",
       "lib/prism/dot_visitor.rb",
diff --git a/test/prism/errors/do_not_allow_trailing_commas_in_method_parameters.txt b/test/prism/errors/3.3-4.0/do_not_allow_trailing_commas_in_method_parameters.txt
similarity index 100%
rename from test/prism/errors/do_not_allow_trailing_commas_in_method_parameters.txt
rename to test/prism/errors/3.3-4.0/do_not_allow_trailing_commas_in_method_parameters.txt
diff --git a/test/prism/errors/4.1/do_not_allow_trailing_commas_after_terminating_arguments.txt b/test/prism/errors/4.1/do_not_allow_trailing_commas_after_terminating_arguments.txt
new file mode 100644
index 00000000000000..b3e06f4154ee58
--- /dev/null
+++ b/test/prism/errors/4.1/do_not_allow_trailing_commas_after_terminating_arguments.txt
@@ -0,0 +1,6 @@
+def foo(a,b,...,);end
+               ^ unexpected `,` in parameters
+
+def foo(a,b,&block,);end
+                  ^ unexpected `,` in parameters
+
diff --git a/test/prism/fixtures/4.1/trailing_comma_after_method_arguments.txt b/test/prism/fixtures/4.1/trailing_comma_after_method_arguments.txt
new file mode 100644
index 00000000000000..ef1385d973f2ef
--- /dev/null
+++ b/test/prism/fixtures/4.1/trailing_comma_after_method_arguments.txt
@@ -0,0 +1,15 @@
+def foo(a,b,c,);end
+
+def foo(a,b,*c,);end
+
+def foo(a,b,*,);end
+
+def foo(a,b,**c,);end
+
+def foo(a,b,**,);end
+
+def foo(
+  a,
+  b,
+  c,
+);end
diff --git a/test/prism/fixtures/heredoc_dedent_line_continuation.txt b/test/prism/fixtures/heredoc_dedent_line_continuation.txt
new file mode 100644
index 00000000000000..661db490c766e1
--- /dev/null
+++ b/test/prism/fixtures/heredoc_dedent_line_continuation.txt
@@ -0,0 +1,5 @@
+<<~FOO
+  foo\
+  \
+  bar
+FOO
diff --git a/test/prism/fixtures_test.rb b/test/prism/fixtures_test.rb
index 3a704b83895054..dcbcb7c117c725 100644
--- a/test/prism/fixtures_test.rb
+++ b/test/prism/fixtures_test.rb
@@ -28,6 +28,8 @@ class FixturesTest < TestCase
     except << "command_method_call_2.txt"
     # https://bugs.ruby-lang.org/issues/21669
     except << "4.1/void_value.txt"
+    # https://bugs.ruby-lang.org/issues/19107
+    except << "4.1/trailing_comma_after_method_arguments.txt"
 
     Fixture.each_for_current_ruby(except: except) do |fixture|
       define_method(fixture.test_name) { assert_valid_syntax(fixture.read) }
diff --git a/test/prism/locals_test.rb b/test/prism/locals_test.rb
index bcb964aff67568..417730a8a73ba6 100644
--- a/test/prism/locals_test.rb
+++ b/test/prism/locals_test.rb
@@ -31,6 +31,9 @@ class LocalsTest < TestCase
 
       # https://bugs.ruby-lang.org/issues/21669
       "4.1/void_value.txt",
+
+      # https://bugs.ruby-lang.org/issues/19107
+      "4.1/trailing_comma_after_method_arguments.txt",
     ]
 
     Fixture.each_for_current_ruby(except: except) do |fixture|
diff --git a/test/prism/ruby/ripper_test.rb b/test/prism/ruby/ripper_test.rb
index 39cb9395ab680e..ba01732bcb2823 100644
--- a/test/prism/ruby/ripper_test.rb
+++ b/test/prism/ruby/ripper_test.rb
@@ -39,6 +39,8 @@ class RipperTest < TestCase
 
     # https://bugs.ruby-lang.org/issues/21669
     incorrect << "4.1/void_value.txt"
+    # https://bugs.ruby-lang.org/issues/19107
+    incorrect << "4.1/trailing_comma_after_method_arguments.txt"
 
     # Skip these tests that we haven't implemented yet.
     omitted_sexp_raw = [
diff --git a/test/prism/ruby/ruby_parser_test.rb b/test/prism/ruby/ruby_parser_test.rb
index 25107978f3828c..bc89bdae72b9bc 100644
--- a/test/prism/ruby/ruby_parser_test.rb
+++ b/test/prism/ruby/ruby_parser_test.rb
@@ -37,6 +37,7 @@ class RubyParserTest < TestCase
       "alias.txt",
       "dsym_str.txt",
       "dos_endings.txt",
+      "heredoc_dedent_line_continuation.txt",
       "heredoc_percent_q_newline_delimiter.txt",
       "heredocs_with_fake_newlines.txt",
       "heredocs_with_ignored_newlines.txt",