diff --git a/lib/zredis/zredis.class.php b/lib/zredis/zredis.class.php
index 7c2074ac6b..45d1c57a50 100644
--- a/lib/zredis/zredis.class.php
+++ b/lib/zredis/zredis.class.php
@@ -166,7 +166,7 @@ class zredis
             $this->update();
         }
 
-        $this->redis->set(zredis::INITIALIZED, date('Y-m-d H:i:s'));
+        $this->redis->setnx(zredis::INITIALIZED, date('Y-m-d H:i:s'));
 
         $this->redis->exec();
     }