diff --git a/index.js b/index.js
index f81fa6d..441abbc 100644
--- a/index.js
+++ b/index.js
@@ -11,6 +11,8 @@ var videostream = require('videostream')
 
 var VIDEOSTREAM_EXTS = [
   '.m4a',
+  '.m4b',
+  '.m4p',
   '.m4v',
   '.mp4'
 ]
@@ -24,6 +26,8 @@ var MEDIASOURCE_VIDEO_EXTS = [
 
 var MEDIASOURCE_AUDIO_EXTS = [
   '.m4a',
+  '.m4b',
+  '.m4p',
   '.mp3'
 ]
 
@@ -348,6 +352,8 @@ function getCodec (name) {
   var extname = path.extname(name).toLowerCase()
   return {
     '.m4a': 'audio/mp4; codecs="mp4a.40.5"',
+    '.m4b': 'audio/mp4; codecs="mp4a.40.5"',
+    '.m4p': 'audio/mp4; codecs="mp4a.40.5"',
     '.m4v': 'video/mp4; codecs="avc1.640029, mp4a.40.5"',
     '.mkv': 'video/webm; codecs="avc1.640029, mp4a.40.5"',
     '.mp3': 'audio/mpeg',
diff --git a/lib/mime.json b/lib/mime.json
index d60e6ce..3ea9e74 100644
--- a/lib/mime.json
+++ b/lib/mime.json
@@ -28,8 +28,10 @@
   ".less": "text/css",
   ".log": "text/plain",
   ".m3u": "audio/x-mpegurl",
-  ".m4a": "audio/mp4",
-  ".m4v": "video/mp4",
+  ".m4a": "audio/x-m4a",
+  ".m4b": "audio/mp4",
+  ".m4p": "audio/mp4",
+  ".m4v": "video/x-m4v",
   ".manifest": "text/cache-manifest",
   ".markdown": "text/x-markdown",
   ".mathml": "application/mathml+xml",