diff --git a/src/MatthiasNoback/MicrosoftOAuth/AccessTokenProvider.php b/src/MatthiasNoback/MicrosoftOAuth/AccessTokenProvider.php
index 068dc36..47c449e 100644
--- a/src/MatthiasNoback/MicrosoftOAuth/AccessTokenProvider.php
+++ b/src/MatthiasNoback/MicrosoftOAuth/AccessTokenProvider.php
@@ -79,7 +79,7 @@ private function authorize($scope, $grantType)
             $response = $this->browser->post(
                 self::OAUTH_URL,
                 array(),
-                http_build_query($requestParameters)
+                http_build_query($requestParameters, null, '&')
             );
         }
         catch (\Exception $previous) {
diff --git a/src/MatthiasNoback/MicrosoftTranslator/ApiCall/AbstractMicrosoftTranslatorApiCall.php b/src/MatthiasNoback/MicrosoftTranslator/ApiCall/AbstractMicrosoftTranslatorApiCall.php
index abcbd14..a8e2f74 100644
--- a/src/MatthiasNoback/MicrosoftTranslator/ApiCall/AbstractMicrosoftTranslatorApiCall.php
+++ b/src/MatthiasNoback/MicrosoftTranslator/ApiCall/AbstractMicrosoftTranslatorApiCall.php
@@ -16,7 +16,7 @@ public function getUrl()
     {
         $url = self::HTTP_API_URL.$this->getApiMethodName();
         if (null !== $queryParameters = $this->getQueryParameters()) {
-            $url .= '?'.http_build_query($queryParameters);
+            $url .= '?'.http_build_query($queryParameters, null, '&');
         }
 
         return $url;