diff --git a/vm_method.c b/vm_method.c
index 96e338c2a1..8c76e892b5 100644
--- a/vm_method.c
+++ b/vm_method.c
@@ -1565,6 +1565,9 @@ rb_alias(VALUE klass, ID alias_name, ID original_name)
 	method_added(target_klass, alias_name);
     }
     else {
+	if (alias_name == original_name) {
+	    return;
+	}
 	rb_method_entry_t *alias_me;
 
 	alias_me = method_entry_set(target_klass, alias_name, orig_me, visi, orig_me->owner);