diff --git a/tools/spec_parser/Dart.g b/tools/spec_parser/Dart.g
index 492efe219a7..64feb04b0fa 100644
--- a/tools/spec_parser/Dart.g
+++ b/tools/spec_parser/Dart.g
@@ -379,7 +379,7 @@ defaultFormalParameter
     ;
 
 defaultNamedParameter
-    :    REQUIRED? normalFormalParameter ('=' expression)?
+    :    metadata REQUIRED? normalFormalParameterNoMetadata ('=' expression)?
     ;
 
 typeWithParameters