diff --git a/src/google/protobuf/inlined_string_field.h b/src/google/protobuf/inlined_string_field.h
index 79e37d414b..71bd6a7eb4 100644
--- a/src/google/protobuf/inlined_string_field.h
+++ b/src/google/protobuf/inlined_string_field.h
@@ -427,7 +427,7 @@ inline PROTOBUF_NDEBUG_INLINE void InlinedStringField::InternalSwap(
     MessageLite* lhs_msg,  //
     InlinedStringField* rhs, Arena* rhs_arena, bool rhs_arena_dtor_registered,
     MessageLite* rhs_msg) {
-#if GOOGLE_PROTOBUF_INTERNAL_DONATE_STEAL_INLINE
+#ifdef GOOGLE_PROTOBUF_INTERNAL_DONATE_STEAL_INLINE
   lhs->get_mutable()->swap(*rhs->get_mutable());
   if (!lhs_arena_dtor_registered && rhs_arena_dtor_registered) {
     lhs_msg->OnDemandRegisterArenaDtor(lhs_arena);