diff --git a/lib/OAuth2/OAuth2.php b/lib/OAuth2/OAuth2.php
index 3a2d084..83aba0a 100644
--- a/lib/OAuth2/OAuth2.php
+++ b/lib/OAuth2/OAuth2.php
@@ -1452,7 +1452,7 @@ protected function getAuthorizationHeader(Request $request)
      *
      * @ingroup oauth2_section_5
      */
-    private function getJsonHeaders()
+    protected function getJsonHeaders()
     {
         return array(
             'Content-Type' => 'application/json',