diff --git a/index.js b/index.js
index 7229750..a1d2ea4 100644
--- a/index.js
+++ b/index.js
@@ -50,7 +50,7 @@ function parse(str) {
   if (str.length > 100) {
     return;
   }
-  var match = /^((?:\d+)?\-?\d?\.?\d+) *(milliseconds?|msecs?|ms|seconds?|secs?|s|minutes?|mins?|m|hours?|hrs?|h|days?|d|weeks?|w|years?|yrs?|y)?$/i.exec(
+  var match = /^((?:\d+)?-?(?:\d+)?\.?\d+) *(milliseconds?|msecs?|ms|seconds?|secs?|s|minutes?|mins?|m|hours?|hrs?|h|days?|d|weeks?|w|years?|yrs?|y)?$/i.exec(
     str
   );
   if (!match) {
diff --git a/tests.js b/tests.js
index 3e94007..9427390 100644
--- a/tests.js
+++ b/tests.js
@@ -71,6 +71,7 @@ describe('ms(string)', function() {
 
   it('should work with negative decimals', function() {
     expect(ms('-1.5h')).to.be(-5400000);
+    expect(ms('-10.5h')).to.be(-37800000);
   });
 
   it('should work with negative decimals starting with "."', function() {