diff --git a/frontend/src/components/test-detail/LiveTimer.tsx b/frontend/src/components/test-detail/LiveTimer.tsx
index a7cf7a4..06000ce 100644
--- a/frontend/src/components/test-detail/LiveTimer.tsx
+++ b/frontend/src/components/test-detail/LiveTimer.tsx
@@ -32,7 +32,10 @@ export default function LiveTimer({
   const isPaused = pausedAt !== null;
 
   useEffect(() => {
-    const start = new Date(startedAt).getTime();
+    // Backend returns naive UTC datetimes without 'Z'. Force UTC so the
+    // browser doesn't misinterpret them as local time (e.g. UTC+2 → 2h off).
+    const utcStr = startedAt.endsWith("Z") || startedAt.includes("+") ? startedAt : startedAt + "Z";
+    const start = new Date(utcStr).getTime();
 
     const tick = () => {
       const now = Date.now();
@@ -40,7 +43,8 @@ export default function LiveTimer({
 
       let totalPaused = pausedSeconds;
       if (isPaused) {
-        const pauseStart = new Date(pausedAt!).getTime();
+        const pausedAtUtc = pausedAt!.endsWith("Z") || pausedAt!.includes("+") ? pausedAt! : pausedAt! + "Z";
+        const pauseStart = new Date(pausedAtUtc).getTime();
         totalPaused += Math.floor((now - pauseStart) / 1000);
       }