diff --git a/index.js b/index.js
index c29aad0..b7b8aa2 100644
--- a/index.js
+++ b/index.js
@@ -26,6 +26,7 @@ var defaultOpts = {
  */
 
 var unitMap = {
+  ms: ['ms', 'milli', 'millisecond', 'milliseconds'],
   s: ['s', 'sec', 'secs', 'second', 'seconds'],
   m: ['m', 'min', 'mins', 'minute', 'minutes'],
   h: ['h', 'hr', 'hrs', 'hour', 'hours'],
@@ -79,6 +80,7 @@ function parseTimestring(string, returnUnit, opts) {
 
 function getUnitValues(opts) {
   var unitValues = {
+    ms: 0.001,
     s: 1,
     m: 60,
     h: 3600,
diff --git a/test.js b/test.js
index 160971d..03ff6f4 100644
--- a/test.js
+++ b/test.js
@@ -5,6 +5,7 @@ var timestring = require('./index');
 
 describe('timestring', function() {
   it('can parse a timestring', function() {
+    expect(timestring('500ms')).to.equal(0.5);
     expect(timestring('1s')).to.equal(1);
     expect(timestring('1m')).to.equal(60);
     expect(timestring('1h')).to.equal(3600);
@@ -15,6 +16,7 @@ describe('timestring', function() {
   });
 
   it('can return a value in a specified unit', function() {
+    expect(timestring('1m', 'ms')).to.equal(60000);
     expect(timestring('5m', 's')).to.equal(300);
     expect(timestring('5m', 'm')).to.equal(5);
   });