diff --git a/src/vim9execute.c b/src/vim9execute.c
index 9f037a3..7ba76e5 100644
--- a/src/vim9execute.c
+++ b/src/vim9execute.c
@@ -737,6 +737,9 @@
     // Put arguments on the stack.
     for (idx = 0; idx < argc; ++idx)
     {
+	if (ufunc->uf_arg_types != NULL && idx < ufunc->uf_args.ga_len
+		&& check_argtype(ufunc->uf_arg_types[idx], &argv[idx]) == FAIL)
+	    goto failed_early;
 	copy_tv(&argv[idx], STACK_TV_BOT(0));
 	++ectx.ec_stack.ga_len;
     }