diff --git a/docs/core-checklist-status.md b/docs/core-checklist-status.md
index 9998c6b..5549916 100644
--- a/docs/core-checklist-status.md
+++ b/docs/core-checklist-status.md
@@ -23,7 +23,7 @@ Legend:
 14. Delivery Status - `DONE` (sent/delivered/read + reconnect reconciliation after backend restarts)
 15. Typing Realtime - `PARTIAL` (typing start/stop done; voice/video typing signals limited)
 16. Media & Attachments - `DONE` (upload/preview/download/gallery)
-17. Voice Messages - `PARTIAL` (record/send/play/seek + global speed 1x/1.5x/2x; UX still being polished)
+17. Voice Messages - `PARTIAL` (record/send/play/seek + global speed 1x/1.5x/2x; recorder now uses mime fallback + chunked capture; UX still being polished)
 18. Circle Video Messages - `PARTIAL` (send/play present, recording UX basic)
 19. Stickers - `PARTIAL` (web sticker picker with preset pack + favorites)
 20. GIF - `PARTIAL` (web GIF picker with Tenor search + preset fallback + favorites)
diff --git a/web/src/components/MessageComposer.tsx b/web/src/components/MessageComposer.tsx
index d40ae60..2573608 100644
--- a/web/src/components/MessageComposer.tsx
+++ b/web/src/components/MessageComposer.tsx
@@ -59,6 +59,24 @@ function saveFavorites(key: string, values: Set<string>): void {
   }
 }
 
+function pickSupportedAudioMimeType(): string | undefined {
+  if (typeof MediaRecorder === "undefined" || typeof MediaRecorder.isTypeSupported !== "function") {
+    return undefined;
+  }
+  const candidates = [
+    "audio/webm;codecs=opus",
+    "audio/webm",
+    "audio/mp4",
+    "audio/ogg;codecs=opus",
+  ];
+  for (const mime of candidates) {
+    if (MediaRecorder.isTypeSupported(mime)) {
+      return mime;
+    }
+  }
+  return undefined;
+}
+
 export function MessageComposer() {
   const activeChatId = useChatStore((s) => s.activeChatId);
   const chats = useChatStore((s) => s.chats);
@@ -562,7 +580,8 @@ export function MessageComposer() {
         }
       }
       const stream = await navigator.mediaDevices.getUserMedia({ audio: true });
-      const recorder = new MediaRecorder(stream);
+      const mimeType = pickSupportedAudioMimeType();
+      const recorder = mimeType ? new MediaRecorder(stream, { mimeType }) : new MediaRecorder(stream);
       recordingStreamRef.current = stream;
       chunksRef.current = [];
       sendVoiceOnStopRef.current = true;
@@ -584,13 +603,19 @@ export function MessageComposer() {
           setUploadError("Voice message is too short. Minimum length is 1 second.");
           return;
         }
-        const blob = new Blob(data, { type: "audio/webm" });
-        const file = new File([blob], `voice-${Date.now()}.webm`, { type: "audio/webm" });
+        const outputMime = recorder.mimeType || mimeType || "audio/webm";
+        const blob = new Blob(data, { type: outputMime });
+        if (blob.size < 512) {
+          setUploadError("Voice message is empty. Please try recording again.");
+          return;
+        }
+        const ext = outputMime.includes("ogg") ? "ogg" : outputMime.includes("mp4") ? "m4a" : "webm";
+        const file = new File([blob], `voice-${Date.now()}.${ext}`, { type: outputMime });
         const waveform = await buildWaveformPoints(blob, 64);
         await handleUpload(file, "voice", waveform);
       };
       recorderRef.current = recorder;
-      recorder.start();
+      recorder.start(250);
       recordingStartedAtRef.current = Date.now();
       setRecordSeconds(0);
       setRecordingState("recording");