diff --git a/server/managers/RssFeedManager.js b/server/managers/RssFeedManager.js
index c4681bdc2..a066a0d32 100644
--- a/server/managers/RssFeedManager.js
+++ b/server/managers/RssFeedManager.js
@@ -2,6 +2,7 @@ const { Request, Response } = require('express')
 const Path = require('path')
 
 const Logger = require('../Logger')
+const { getAudioMimeTypeFromExtname } = require('../utils/fileUtils')
 const SocketAuthority = require('../SocketAuthority')
 const Database = require('../Database')
 
@@ -216,6 +217,11 @@ class RssFeedManager {
       res.sendStatus(404)
       return
     }
+    // Express does not set the correct mimetype for m4b files so use our defined mimetypes if available
+    const audioMimeType = getAudioMimeTypeFromExtname(Path.extname(episodePath))
+    if (audioMimeType) {
+      res.setHeader('Content-Type', audioMimeType)
+    }
     res.sendFile(episodePath)
   }