diff --git a/MoodleRest.php b/MoodleRest.php
index fc4cdab..9d13a28 100644
--- a/MoodleRest.php
+++ b/MoodleRest.php
@@ -416,7 +416,7 @@ public function request($function, $parameters = null, $method = self::METHOD_GE
 
         $this->setMethod($method);
 
-        $query_string = is_array($parameters) ? http_build_query($parameters) : '';
+        $query_string = is_array($parameters) ? http_build_query($parameters, '', '&') : '';
 
         $this->setUrl(
             $this->getServerAddress() .