diff --git a/lib/Predis/ConnectionParameters.php b/lib/Predis/ConnectionParameters.php
index 86089a90..2e6a14c6 100644
--- a/lib/Predis/ConnectionParameters.php
+++ b/lib/Predis/ConnectionParameters.php
@@ -118,6 +118,10 @@ class ConnectionParameters implements IConnectionParameters {
     }
 
     public function __isset($parameter) {
+        return isset($this->_parameters[$parameter]);
+    }
+
+    public function setByUser($parameter) {
         return in_array($parameter, $this->_userDefined);
     }