diff --git a/src/dmd/asttypename.d b/src/dmd/asttypename.d
index a49a9834d9..b5e17979ec 100644
--- a/src/dmd/asttypename.d
+++ b/src/dmd/asttypename.d
@@ -73,7 +73,7 @@ string astTypeName(RootObject node)
     }
 }
 
-enum mixin_string =
+extern(D) enum mixin_string =
 ({
     string astTypeNameFunctions;
     string visitOverloads;