diff --git a/diagnostic/index.html b/diagnostic/index.html
index 9625597..dc15eb9 100644
--- a/diagnostic/index.html
+++ b/diagnostic/index.html
@@ -746,7 +746,16 @@
           document.getElementById('diag-speed-thorsten').value = st;
           document.getElementById('speed-thorsten-label').textContent = st + 'x';
           document.getElementById('diag-tts-engine').value = msg.ttsEngine || 'piper';
-          document.getElementById('diag-xtts-voice').value = msg.xttsVoice || '';
+          // XTTS-Voice setzen — Option hinzufuegen falls nicht vorhanden
+          const xttsSelect = document.getElementById('diag-xtts-voice');
+          const xttsVoice = msg.xttsVoice || '';
+          if (xttsVoice && !Array.from(xttsSelect.options).some(o => o.value === xttsVoice)) {
+            const opt = document.createElement('option');
+            opt.value = xttsVoice;
+            opt.textContent = xttsVoice;
+            xttsSelect.appendChild(opt);
+          }
+          xttsSelect.value = xttsVoice;
           toggleXTTSPanel();
           return;
         }