diff --git a/src/Composer/Repository/Vcs/BitbucketDriver.php b/src/Composer/Repository/Vcs/BitbucketDriver.php
index e1c45acdef10..1a9a8f6d8bb9 100644
--- a/src/Composer/Repository/Vcs/BitbucketDriver.php
+++ b/src/Composer/Repository/Vcs/BitbucketDriver.php
@@ -86,7 +86,7 @@ protected function getRepoData()
             $this->repository,
             http_build_query(
                 array('fields' => '-project,-owner'),
-                null,
+                '',
                 '&'
             )
         );
@@ -286,7 +286,7 @@ public function getTags()
                         'fields' => 'values.name,values.target.hash,next',
                         'sort' => '-target.date',
                     ),
-                    null,
+                    '',
                     '&'
                 )
             );
@@ -330,7 +330,7 @@ public function getBranches()
                         'fields' => 'values.name,values.target.hash,values.heads,next',
                         'sort' => '-target.date',
                     ),
-                    null,
+                    '',
                     '&'
                 )
             );
diff --git a/src/Composer/Util/GitLab.php b/src/Composer/Util/GitLab.php
index 1ff2fbb96e61..1345eaff3844 100644
--- a/src/Composer/Util/GitLab.php
+++ b/src/Composer/Util/GitLab.php
@@ -172,7 +172,7 @@ private function createToken($scheme, $originUrl)
             'username' => $username,
             'password' => $password,
             'grant_type' => 'password',
-        ), null, '&');
+        ), '', '&');
         $options = array(
             'retry-auth-failure' => false,
             'http' => array(