diff --git a/kv/util/engine_util/cf_iterator.go b/kv/util/engine_util/cf_iterator.go
index 72c9f67f..6a9e4e06 100644
--- a/kv/util/engine_util/cf_iterator.go
+++ b/kv/util/engine_util/cf_iterator.go
@@ -76,7 +76,7 @@ func (it *BadgerIterator) Item() DBItem {
 func (it *BadgerIterator) Valid() bool { return it.iter.ValidForPrefix([]byte(it.prefix)) }
 
 func (it *BadgerIterator) ValidForPrefix(prefix []byte) bool {
-	return it.iter.ValidForPrefix(append(prefix, []byte(it.prefix)...))
+	return it.iter.ValidForPrefix(append([]byte(it.prefix), prefix...))
 }
 
 func (it *BadgerIterator) Close() {