diff --git a/lib/less/parser.js b/lib/less/parser.js
index 325565a7..a2bd759b 100644
--- a/lib/less/parser.js
+++ b/lib/less/parser.js
@@ -563,7 +563,7 @@ less.Parser = function Parser(env) {
                 // The arguments are parsed with the `entities.arguments` parser.
                 //
                 call: function () {
-                    var name, args, index = i;
+                    var name, args, alpha_ret, index = i;
 
                     if (! (name = /^([\w-]+|%|progid:[\w\.]+)\(/.exec(chunks[j]))) return;
 
@@ -572,7 +572,12 @@ less.Parser = function Parser(env) {
                     if (name === 'url') { return null }
                     else                { i += name.length }
 
-                    if (name === 'alpha') { return $(this.alpha) }
+                    if (name === 'alpha') {
+                        alpha_ret = $(this.alpha);
+                        if(typeof alpha_ret !== 'undefined') {
+                            return alpha_ret;
+                        }
+                    }
 
                     $('('); // Parse the '(' and consume whitespace.
 
diff --git a/test/css/colors.css b/test/css/colors.css
index 77ab7a88..8ff5bad1 100644
--- a/test/css/colors.css
+++ b/test/css/colors.css
@@ -60,3 +60,18 @@
   color: transparent;
   background-color: rgba(0, 0, 0, 0);
 }
+#alpha #fromvar {
+  opacity: 0.7;
+}
+#alpha #short {
+  opacity: 1;
+}
+#alpha #long {
+  opacity: 1;
+}
+#alpha #rgba {
+  opacity: 0.2;
+}
+#alpha #hsl {
+  opacity: 1;
+}
diff --git a/test/less/colors.less b/test/less/colors.less
index d4c6a851..d8038de8 100644
--- a/test/less/colors.less
+++ b/test/less/colors.less
@@ -66,5 +66,23 @@
 
 .transparent {
     color: transparent;
-	background-color: rgba(0, 0, 0, 0);
-}
\ No newline at end of file
+    background-color: rgba(0, 0, 0, 0);
+}
+#alpha {
+    @colorvar: rgba(150, 200, 150, 0.7);
+    #fromvar {
+        opacity: alpha(@colorvar);
+    }
+    #short {
+        opacity: alpha(#aaa);
+    }
+    #long {
+        opacity: alpha(#bababa);
+    }
+    #rgba {
+        opacity: alpha(rgba(50, 120, 95, 0.2));
+    }
+    #hsl {
+        opacity: alpha(hsl(120, 100%, 50%));
+    }
+}