diff --git a/py/compile.c b/py/compile.c
index b3a8371..48c9c08 100644
--- a/py/compile.c
+++ b/py/compile.c
@@ -3312,7 +3312,8 @@
         return mp_const_true;
 #else
         // return function that executes the outer module
-        return rt_make_function_from_id(unique_code_id, MP_OBJ_NULL);
+        // we can free the unique_code slot because no-one has reference to this unique_code_id anymore
+        return rt_make_function_from_id(unique_code_id, true, MP_OBJ_NULL);
 #endif
     }
 }