diff --git a/admin/code/LeftAndMain.php b/admin/code/LeftAndMain.php
index 38b2bb21f..e1e27983c 100644
--- a/admin/code/LeftAndMain.php
+++ b/admin/code/LeftAndMain.php
@@ -353,7 +353,9 @@ class LeftAndMain extends Controller implements PermissionProvider {
 	function redirect($url, $code=302) {
 		if($this->request->isAjax()) {
 			$this->response->addHeader('X-ControllerURL', $url);
-			if($header = $this->request->getHeader('X-Pjax')) $this->response->addHeader('X-Pjax', $header);
+			if($this->request->getHeader('X-Pjax') && !$this->response->getHeader('X-Pjax')) {
+				$this->response->addHeader('X-Pjax', $this->request->getHeader('X-Pjax'));
+			}
 			return ''; // Actual response will be re-requested by client
 		} else {
 			parent::redirect($url, $code);