diff --git a/lib/less/tree/call.js b/lib/less/tree/call.js
index c1465dd4..7c2d21e6 100644
--- a/lib/less/tree/call.js
+++ b/lib/less/tree/call.js
@@ -36,7 +36,7 @@ tree.Call.prototype = {
             }
         } else { // 2.
             return new(tree.Anonymous)(this.name +
-                   "(" + args.map(function (a) { return a.toCSS() }).join(', ') + ")");
+                   "(" + args.map(function (a) { return a.toCSS(env) }).join(', ') + ")");
         }
     },
 
diff --git a/test/css/functions.css b/test/css/functions.css
index 7a595f70..933370b1 100644
--- a/test/css/functions.css
+++ b/test/css/functions.css
@@ -4,6 +4,7 @@
   height: undefined("self");
   border-width: 5;
   variable: 11;
+  background: linear-gradient(#000000, #ffffff);
 }
 #built-in {
   escaped: -Some::weird(#thing, y);
diff --git a/test/less/functions.less b/test/less/functions.less
index 7e599e23..0eb3bad4 100644
--- a/test/less/functions.less
+++ b/test/less/functions.less
@@ -1,10 +1,12 @@
 #functions {
   @var: 10;
+  @colors: #000, #fff;
   color: _color("evil red"); // #660000
   width: increment(15);
   height: undefined("self");
   border-width: add(2, 3);
   variable: increment(@var);
+  background: linear-gradient(@colors);
 }
 
 #built-in {