diff --git a/lib/less/functions.js b/lib/less/functions.js
index 80fea56e..ea7c2d16 100644
--- a/lib/less/functions.js
+++ b/lib/less/functions.js
@@ -209,6 +209,9 @@ tree.functions = {
         str = str.replace(/%%/g, '%');
         return new(tree.Quoted)('"' + str + '"', str);
     },
+    unit: function (val, unit) {
+        return new(tree.Dimension)(val.value, unit ? unit.toCSS() : "");
+    },
     round: function (n, f) {
         var fraction = typeof(f) === "undefined" ? 0 : f.value;
         if (n instanceof tree.Dimension) {
diff --git a/test/css/functions.css b/test/css/functions.css
index c0c51e84..0b80cfe7 100644
--- a/test/css/functions.css
+++ b/test/css/functions.css
@@ -42,6 +42,8 @@
   format-multiple: "hello earth 2";
   format-url-encode: "red is %23ff0000";
   eformat: rgb(32, 128, 64);
+  unitless: 12;
+  unit: 14em;
   hue: 98;
   saturation: 12%;
   lightness: 95%;
diff --git a/test/less/functions.less b/test/less/functions.less
index 274ce49c..41244fbf 100644
--- a/test/less/functions.less
+++ b/test/less/functions.less
@@ -46,6 +46,9 @@
   format-multiple: %("hello %s %d", "earth", 2);
   format-url-encode: %('red is %A', #ff0000);
   eformat: e(%("rgb(%d, %d, %d)", @r, 128, 64));
+  
+  unitless: unit(12px);
+  unit: unit(13px + 1px, em);
 
   hue: hue(hsl(98, 12%, 95%));
   saturation: saturation(hsl(98, 12%, 95%));