diff --git a/lib/grammar.js b/lib/grammar.js
index 0a07164..3459633 100644
--- a/lib/grammar.js
+++ b/lib/grammar.js
@@ -47,12 +47,14 @@ var grammar = module.exports = {
   a: [
     { //a=rtpmap:110 opus/48000/2
       push: 'rtp',
-      reg: /^rtpmap:(\d*) ([\w\-]*)\/(\d*)(?:\s*\/(\S*))?/,
+      reg: /^rtpmap:(\d*) ([\w\-]*)(?:\s*\/(\d*)(?:\s*\/(\S*))?)?/,
       names: ['payload', 'codec', 'rate', 'encoding'],
       format: function (o) {
         return (o.encoding) ?
           "rtpmap:%d %s/%s/%s":
-          "rtpmap:%d %s/%s";
+          o.rate ?
+          "rtpmap:%d %s/%s":
+          "rtpmap:%d %s";
       }
     },
     {
diff --git a/test/alac.sdp b/test/alac.sdp
new file mode 100644
index 0000000..1b21f28
--- /dev/null
+++ b/test/alac.sdp
@@ -0,0 +1,10 @@
+v=0
+o=iTunes 3413821438 0 IN IP4 fe80::217:f2ff:fe0f:e0f6
+s=iTunes
+c=IN IP4 fe80::5a55:caff:fe1a:e187
+t=0 0
+m=audio 0 RTP/AVP 96
+a=rtpmap:96 AppleLossless
+a=fmtp:96 352 0 16 40 10 14 2 255 0 0 44100
+a=fpaeskey:RlBMWQECAQAAAAA8AAAAAPFOnNe+zWb5/n4L5KZkE2AAAAAQlDx69reTdwHF9LaNmhiRURTAbcL4brYAceAkZ49YirXm62N4
+a=aesiv:5b+YZi9Ikb845BmNhaVo+Q
diff --git a/test/parse.test.js b/test/parse.test.js
index afcc407..b940890 100644
--- a/test/parse.test.js
+++ b/test/parse.test.js
@@ -325,3 +325,30 @@ exports.jsepSdp = function (t) {
     t.done();
   });
 };
+
+exports.alacSdp = function (t) {
+  fs.readFile(__dirname + '/alac.sdp', function (err, sdp) {
+    if (err) {
+      t.ok(false, "failed to read file:" + err);
+      t.done();
+      return;
+    }
+    var session = parse(sdp+'');
+    t.ok(session, "got session info");
+    var media = session.media;
+    t.ok(media && media.length > 0, "got media");
+
+    console.log(require('util').inspect(session, {depth: null}));
+
+    var audio = media[0];
+    t.equal(audio.type, "audio", "audio type");
+    t.equal(audio.protocol, "RTP/AVP", "audio protocol");
+    t.equal(audio.fmtp[0].payload, 96, "audio fmtp 0 payload");
+    t.equal(audio.fmtp[0].config, "352 0 16 40 10 14 2 255 0 0 44100", "audio fmtp 0 config");
+    t.equal(audio.rtp[0].payload, 96, "audio rtp 0 payload");
+    t.equal(audio.rtp[0].codec, "AppleLossless", "audio rtp 0 codec");
+    t.equal(audio.rtp[0].rate, undefined, "audio rtp 0 rate");
+
+    t.done();
+  });
+};