diff --git a/lemonldap-ng-common/lib/Lemonldap/NG/Common/Conf/Backends/MongoDB.pm b/lemonldap-ng-common/lib/Lemonldap/NG/Common/Conf/Backends/MongoDB.pm
index 8d568a2b5..ba32a3116 100644
--- a/lemonldap-ng-common/lib/Lemonldap/NG/Common/Conf/Backends/MongoDB.pm
+++ b/lemonldap-ng-common/lib/Lemonldap/NG/Common/Conf/Backends/MongoDB.pm
@@ -80,7 +80,7 @@ sub store {
         $Lemonldap::NG::Common::Conf::msg .= "Unable to store conf: $@\n";
         return 0;
     }
-    return $res;
+    return $fields->{cfgNum};
 }
 
 sub load {