--- a/build/config/compiler/BUILD.gn
+++ b/build/config/compiler/BUILD.gn
@@ -2033,5 +2033,5 @@ config("compiler") {
   if (use_safe_libcxx) {
     defines += [ "_LIBCPP_HARDENING_MODE=_LIBCPP_HARDENING_MODE_EXTENSIVE" ]
-  } else {
+  } else if (use_custom_libcxx) {
     defines += [ "_LIBCPP_HARDENING_MODE=_LIBCPP_HARDENING_MODE_NONE" ]
   }