diff --git a/frontend/src/tools/nachrichten.jsx b/frontend/src/tools/nachrichten.jsx
index 7c1dcc9..1d363d2 100644
--- a/frontend/src/tools/nachrichten.jsx
+++ b/frontend/src/tools/nachrichten.jsx
@@ -388,7 +388,9 @@ function InfoBox({ color, children }) {
 }
 
 function formatMsgTime(isoStr) {
-  const d   = new Date((isoStr || '').replace(' ', 'T'));
+  if (!isoStr) return '';
+  const d   = new Date(isoStr.replace(' ', 'T'));
+  if (isNaN(d)) return '';
   const now = new Date();
   const isToday    = d.toDateString() === now.toDateString();
   const isThisYear = d.getFullYear() === now.getFullYear();