diff --git a/src/Http/Controllers/CP/SessionTimeoutController.php b/src/Http/Controllers/CP/SessionTimeoutController.php
index 4278b61614..f4091039e6 100644
--- a/src/Http/Controllers/CP/SessionTimeoutController.php
+++ b/src/Http/Controllers/CP/SessionTimeoutController.php
@@ -13,8 +13,8 @@ public function __invoke()
         // remember me would have already been served a 403 error and wouldn't have got this far.
         $lastActivity = session('last_activity', now()->timestamp);
 
-        return Carbon::createFromTimestamp($lastActivity, config('app.timezone'))
+        return abs((int) Carbon::createFromTimestamp($lastActivity, config('app.timezone'))
             ->addMinutes((int) config('session.lifetime'))
-            ->diffInSeconds();
+            ->diffInSeconds());
     }
 }