diff --git a/src/Composer/Util/RemoteFilesystem.php b/src/Composer/Util/RemoteFilesystem.php
index 133521a39..3c3326653 100644
--- a/src/Composer/Util/RemoteFilesystem.php
+++ b/src/Composer/Util/RemoteFilesystem.php
@@ -233,7 +233,10 @@ class RemoteFilesystem
         $origFileUrl = $fileUrl;
 
         if (isset($options['github-token'])) {
-            $fileUrl .= (false === strpos($fileUrl, '?') ? '?' : '&') . 'access_token='.$options['github-token'];
+            // only add the access_token if it is actually a github URL (in case we were redirected to S3)
+            if (preg_match('{^https?://([a-z0-9-]+\.)*github\.com/}', $fileUrl)) {
+                $fileUrl .= (false === strpos($fileUrl, '?') ? '?' : '&') . 'access_token='.$options['github-token'];
+            }
             unset($options['github-token']);
         }