diff --git a/lib/Doctrine/DBAL/Driver/SQLSrv/Driver.php b/lib/Doctrine/DBAL/Driver/SQLSrv/Driver.php
index 2b84a0fcf81..a9be26e9dea 100644
--- a/lib/Doctrine/DBAL/Driver/SQLSrv/Driver.php
+++ b/lib/Doctrine/DBAL/Driver/SQLSrv/Driver.php
@@ -31,8 +31,13 @@ public function connect(array $params, $username = null, $password = null, array
             $driverOptions['CharacterSet'] = $params['charset'];
         }
 
-        $driverOptions['UID'] = $username;
-        $driverOptions['PWD'] = $password;
+        if ($username !== null) {
+            $driverOptions['UID'] = $username;
+        }
+
+        if ($password !== null) {
+            $driverOptions['PWD'] = $password;
+        }
 
         if (! isset($driverOptions['ReturnDatesAsStrings'])) {
             $driverOptions['ReturnDatesAsStrings'] = 1;