diff --git a/include/classes/mysqlims.class.php b/include/classes/mysqlims.class.php
index 85042774..3c5d9ba7 100644
--- a/include/classes/mysqlims.class.php
+++ b/include/classes/mysqlims.class.php
@@ -77,7 +77,7 @@ class mysqlims extends mysqli
      */
     public function query($query, $resultmode = MYSQLI_STORE_RESULT)
     {
-        if (stripos($query, "SELECT") && stripos($query, "FOR UPDATE") === false && $this->mysqliR !== null) {/* Use readonly server */
+        if (stripos($query, "SELECT") && stripos($query, "FOR UPDATE") === false && $this->slave !== false) {/* Use readonly server */
             return $this->mysqliR->query($query, $resultmode);
         } else {
             return $this->mysqliW->query($query, $resultmode);