diff --git a/class.c b/class.c
index f0b6ba0c07..263cb759ca 100644
--- a/class.c
+++ b/class.c
@@ -1804,15 +1804,12 @@ static void
 unknown_keyword_error(VALUE hash, const ID *table, int keywords)
 {
     st_table *tbl = rb_hash_tbl_raw(hash);
-    VALUE keys;
     int i;
     for (i = 0; i < keywords; i++) {
 	st_data_t key = ID2SYM(table[i]);
 	st_delete(tbl, &key, NULL);
     }
-    keys = rb_funcallv(hash, rb_intern("keys"), 0, 0);
-    if (!RB_TYPE_P(keys, T_ARRAY)) rb_raise(rb_eArgError, "unknown keyword");
-    rb_keyword_error("unknown", keys);
+    rb_keyword_error("unknown", rb_hash_keys(hash));
 }
 
 static int