diff --git a/lib/less/functions.js b/lib/less/functions.js
index 8da556de..7e199938 100644
--- a/lib/less/functions.js
+++ b/lib/less/functions.js
@@ -179,8 +179,15 @@ tree.functions = {
         str = str.replace(/%%/g, '%');
         return new(tree.Quoted)('"' + str + '"', str);
     },
-    round: function (n) {
-        return this._math('round', n);
+    round: function (n, f) {
+        var fraction = typeof(f) === "undefined" ? 0 : f.value;
+        if (n instanceof tree.Dimension) {
+            return new(tree.Dimension)(number(n).toFixed(fraction), n.unit);
+        } else if (typeof(n) === 'number') {
+            return n.toFixed(fraction);
+        } else {
+            throw { type: "Argument", message: "argument must be a number" };
+        }
     },
     ceil: function (n) {
         return this._math('ceil', n);