diff --git a/htdocs/core/class/translate.class.php b/htdocs/core/class/translate.class.php
index 3602ae427bd..bdcae2e33ea 100644
--- a/htdocs/core/class/translate.class.php
+++ b/htdocs/core/class/translate.class.php
@@ -577,7 +577,7 @@ class Translate
             //$newstr=$this->getLabelFromKey($db,$reg[1],'c_ordersource','code','label');
         }
 
-        if ($conf->global->MAIN_FEATURES_LEVEL >= 2) dol_syslog(__METHOD__." missing translation for key '".$newstr."' in ".$_SERVER["PHP_SELF"], LOG_DEBUG);
+        if (! empty($conf->global->MAIN_FEATURES_LEVEL) && $conf->global->MAIN_FEATURES_LEVEL >= 2) dol_syslog(__METHOD__." missing translation for key '".$newstr."' in ".$_SERVER["PHP_SELF"], LOG_DEBUG);
 
         return $newstr;
 	}