diff --git a/modules/oauth2/lib/DrupalOAuth2Client.inc b/modules/oauth2/lib/DrupalOAuth2Client.inc
index 0b25a20..558952e 100644
--- a/modules/oauth2/lib/DrupalOAuth2Client.inc
+++ b/modules/oauth2/lib/DrupalOAuth2Client.inc
@@ -93,7 +93,7 @@ class DrupalOAuth2Client extends DrupalOAuthClient {
       }
     }
     if (!empty($params)) {
-      $url .= '?' . http_build_query($params);
+      $url .= '?' . drupal_http_build_query($params);
     }
     $headers = array(
       'Accept: application/x-www-form-urlencoded',
@@ -104,7 +104,7 @@ class DrupalOAuth2Client extends DrupalOAuthClient {
     curl_setopt($ch, CURLOPT_URL, $url);
     if (!$options['get']) {
       curl_setopt($ch, CURLOPT_POST, 1);
-      curl_setopt($ch, CURLOPT_POSTFIELDS, http_build_query($params)); // required for Google+?
+      curl_setopt($ch, CURLOPT_POSTFIELDS, drupal_http_build_query($params)); // required for Google+?
     }
     $oauth_version = _oauth_common_version();
     curl_setopt($ch, CURLOPT_USERAGENT, 'Drupal/' . VERSION . ' OAuth/' . $oauth_version);
@@ -127,4 +127,4 @@ class DrupalOAuth2Client extends DrupalOAuthClient {
     return $result->body;
   }
 
-}
\ No newline at end of file
+}