diff --git a/src/regexp/jsregexp-inl.h b/src/regexp/jsregexp-inl.h
index 756210b218..926fec2868 100644
--- a/src/regexp/jsregexp-inl.h
+++ b/src/regexp/jsregexp-inl.h
@@ -75,6 +75,10 @@ int32_t* RegExpImpl::GlobalCache::LastSuccessfulMatch() {
   return &register_array_[index];
 }
 
+RegExpEngine::CompilationResult::CompilationResult(Isolate* isolate,
+                                                   const char* error_message)
+    : error_message(error_message),
+      code(ReadOnlyRoots(isolate).the_hole_value()) {}
 
 }  // namespace internal
 }  // namespace v8
diff --git a/src/regexp/jsregexp.h b/src/regexp/jsregexp.h
index e2d41febb4..0c4def20e8 100644
--- a/src/regexp/jsregexp.h
+++ b/src/regexp/jsregexp.h
@@ -1504,15 +1504,12 @@ struct RegExpCompileData {
 class RegExpEngine: public AllStatic {
  public:
   struct CompilationResult {
-    CompilationResult(Isolate* isolate, const char* error_message)
-        : error_message(error_message),
-          code(ReadOnlyRoots(isolate).the_hole_value()),
-          num_registers(0) {}
+    inline CompilationResult(Isolate* isolate, const char* error_message);
     CompilationResult(Object* code, int registers)
-        : error_message(nullptr), code(code), num_registers(registers) {}
-    const char* error_message;
-    Object* code;
-    int num_registers;
+        : code(code), num_registers(registers) {}
+    const char* const error_message = nullptr;
+    Object* const code;
+    int const num_registers = 0;
   };
 
   static CompilationResult Compile(Isolate* isolate, Zone* zone,
diff --git a/tools/generate-header-include-checks.py b/tools/generate-header-include-checks.py
index 7316d9bbcc..a76be5be1c 100755
--- a/tools/generate-header-include-checks.py
+++ b/tools/generate-header-include-checks.py
@@ -29,7 +29,6 @@ AUTO_EXCLUDE = [
   # flag-definitions.h needs a mode set for being included.
   'src/flag-definitions.h',
   # blacklist of headers we need to fix (https://crbug.com/v8/7965).
-  'src/regexp/jsregexp.h',
   'src/transitions.h',
 ]
 AUTO_EXCLUDE_PATTERNS = [