diff --git a/src/vim9execute.c b/src/vim9execute.c
index 31b1274..b389891 100644
--- a/src/vim9execute.c
+++ b/src/vim9execute.c
@@ -806,7 +806,7 @@
     funccal_entry_T entry;
 
     save_funccal(&entry);
-    set_var_const(name, NULL, tv, FALSE, ASSIGN_NO_DECL);
+    set_var_const(name, NULL, tv, FALSE, ASSIGN_DECL);
     restore_funccal();
 }