diff --git a/lib/less/functions.js b/lib/less/functions.js
index b302641a..00d00e30 100644
--- a/lib/less/functions.js
+++ b/lib/less/functions.js
@@ -67,6 +67,16 @@ tree.functions = {
     },
     e: function (str) {
         return new(tree.Anonymous)(str);
+    },
+    '%': function (quoted /* arg, arg, ...*/) {
+        var args = Array.prototype.slice.call(arguments, 1),
+            str = quoted.content;
+
+        for (var i = 0; i < args.length; i++) {
+            str = str.replace(/%[sd]/, args[i].toCSS());
+        }
+        str = str.replace(/%%/g, '%');
+        return new(tree.Quoted)('"' + str + '"', str);
     }
 };
 
diff --git a/lib/less/parser.js b/lib/less/parser.js
index 3dc199c2..31e02a38 100644
--- a/lib/less/parser.js
+++ b/lib/less/parser.js
@@ -364,7 +364,7 @@ less.Parser = function Parser(env) {
                 call: function () {
                     var name, args;
 
-                    if (! (name = $(/([a-zA-Z0-9_-]+)\(/g))) return;
+                    if (! (name = $(/([a-zA-Z0-9_-]+|%)\(/g))) return;
 
                     if (name[1].toLowerCase() === 'alpha') { return $(this.alpha) }