diff --git a/lib/less/tree/operation.js b/lib/less/tree/operation.js
index 24c64a6..b89a843 100644
--- a/lib/less/tree/operation.js
+++ b/lib/less/tree/operation.js
@@ -5,13 +5,18 @@ tree.Operation = function Operation(op, operands) {
     this.operands = operands;
 };
 tree.Operation.prototype.eval = function (env) {
-    var a = this.operands[0],
-        b = this.operands[1],
+    var a = this.operands[0].eval(env),
+        b = this.operands[1].eval(env),
         temp;
 
-    if (a instanceof tree.Dimension) {
-        temp = b, b = a, a = temp;
+    if (a instanceof tree.Dimension && b instanceof tree.Color) {
+        if (this.op === '*' || this.op === '+') {
+            temp = b, b = a, a = temp;
+        } else {
+            throw { name: "OperationError",
+                    message: "Can't substract or divide a color from a number" };
+        }
     }
-    return a.eval(env).operate(this.op, b.eval(env));
+    return a.operate(this.op, b);
 };
 
diff --git a/test/css/operations.css b/test/css/operations.css
index f419357..930a758 100644
--- a/test/css/operations.css
+++ b/test/css/operations.css
@@ -16,9 +16,11 @@
   height: 0px;
   width: 4px;
 }
-.shorthands { padding: -1px 2px 0 -4px; }
+.shorthands {
+  padding: -1px 2px 0 -4px;
+}
 .colors {
-  color: #112233;
+  color: #123;
   border-color: #334455;
   background-color: #000000;
 }