diff --git a/lib/SimpleSAML/Utils/HTTP.php b/lib/SimpleSAML/Utils/HTTP.php
index 186ee6ed19c5f9342388bbaec2625b9a7ebffd05..068a8a66ec91d680210e5d3b9ac767336ac77df9 100644
--- a/lib/SimpleSAML/Utils/HTTP.php
+++ b/lib/SimpleSAML/Utils/HTTP.php
@@ -830,6 +830,10 @@ class HTTP
         }
 
         $res = array();
+        if (empty($query_string)) {
+            return $res;
+        }
+
         foreach (explode('&', $query_string) as $param) {
             $param = explode('=', $param);
             $name = urldecode($param[0]);