diff --git a/src/version.c b/src/version.c
index a2e66b2..73093f4 100644
--- a/src/version.c
+++ b/src/version.c
@@ -700,6 +700,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    628,
+/**/
     627,
 /**/
     626,
diff --git a/src/vim9type.c b/src/vim9type.c
index c4aec7b..771fbf5 100644
--- a/src/vim9type.c
+++ b/src/vim9type.c
@@ -485,18 +485,13 @@
 		    {
 			type->tt_argcount -= tv->vval.v_partial->pt_argc;
 			type->tt_min_argcount -= tv->vval.v_partial->pt_argc;
-			if (type->tt_argcount <= 0)
-			    type->tt_args = NULL;
-			else
-			{
-			    int i;
-
-			    func_type_add_arg_types(type, type->tt_argcount,
-								     type_gap);
-			    for (i = 0; i < type->tt_argcount; ++i)
-				type->tt_args[i] = ufunc->uf_func_type->tt_args[
+			if (type->tt_argcount > 0
+				&& func_type_add_arg_types(type,
+					    type->tt_argcount, type_gap) == OK)
+			    for (int i = 0; i < type->tt_argcount; ++i)
+				type->tt_args[i] =
+					ufunc->uf_func_type->tt_args[
 					      i + tv->vval.v_partial->pt_argc];
-			}
 		    }
 		    return type;
 		}