diff --git a/packages/backend/src/routes/music.ts b/packages/backend/src/routes/music.ts
index c7627c8..118452d 100644
--- a/packages/backend/src/routes/music.ts
+++ b/packages/backend/src/routes/music.ts
@@ -416,4 +416,42 @@ router.post('/fix-orphaned', async (req, res) => {
   }
 });
 
+/**
+ * Fix incorrect or missing content types for existing MusicFile documents
+ */
+router.post('/fix-content-types', async (req, res) => {
+  try {
+    const guessContentType = (fileName: string): string => {
+      const ext = (fileName.split('.').pop() || '').toLowerCase();
+      switch (ext) {
+        case 'mp3': return 'audio/mpeg';
+        case 'wav': return 'audio/wav';
+        case 'flac': return 'audio/flac';
+        case 'm4a': return 'audio/mp4';
+        case 'aac': return 'audio/aac';
+        case 'ogg': return 'audio/ogg';
+        case 'opus': return 'audio/opus';
+        case 'wma': return 'audio/x-ms-wma';
+        default: return 'application/octet-stream';
+      }
+    };
+
+    const files = await MusicFile.find({});
+    let updated = 0;
+    for (const mf of files) {
+      const expected = guessContentType(mf.originalName || mf.s3Key);
+      if (!mf.contentType || mf.contentType !== expected) {
+        mf.contentType = expected;
+        await mf.save();
+        updated++;
+      }
+    }
+
+    res.json({ message: 'Content types fixed', updated });
+  } catch (error) {
+    console.error('Error fixing content types:', error);
+    res.status(500).json({ message: 'Error fixing content types', error });
+  }
+});
+
 export { router as musicRouter }; 
\ No newline at end of file