diff --git a/lib/user.php b/lib/user.php
index 31be3f20db8..a161868c8c2 100644
--- a/lib/user.php
+++ b/lib/user.php
@@ -652,5 +652,10 @@ class OC_User {
 		setcookie('oc_username', '', time()-3600, \OC::$WEBROOT);
 		setcookie('oc_token', '', time()-3600, \OC::$WEBROOT);
 		setcookie('oc_remember_login', '', time()-3600, \OC::$WEBROOT);
+		// old cookies might be stored under /webroot/ instead of /webroot
+		// and Firefox doesn't like it!
+		setcookie('oc_username', '', time()-3600, \OC::$WEBROOT . '/');
+		setcookie('oc_token', '', time()-3600, \OC::$WEBROOT . '/');
+		setcookie('oc_remember_login', '', time()-3600, \OC::$WEBROOT . '/');
 	}
 }