diff --git a/src/scripting/vmthunks.cpp b/src/scripting/vmthunks.cpp
index 15124fe9ee..c6998fec2f 100644
--- a/src/scripting/vmthunks.cpp
+++ b/src/scripting/vmthunks.cpp
@@ -2484,7 +2484,7 @@ static void ZGetUDMFString(int type, int index, int key, FString *result)
 	*result = GetUDMFString(type, index, ENamedName(key));
 }
 
-DEFINE_ACTION_FUNCTION(FLevelLocals, GetUDMFString, ZGetUDMFString)
+DEFINE_ACTION_FUNCTION_NATIVE(FLevelLocals, GetUDMFString, ZGetUDMFString)
 {
 	PARAM_SELF_STRUCT_PROLOGUE(FLevelLocals);
 	PARAM_INT(type);