diff --git a/lib/clean.js b/lib/clean.js
index 3c134b2e6..d8da80cb4 100644
--- a/lib/clean.js
+++ b/lib/clean.js
@@ -141,7 +141,8 @@ var CleanCSS = {
     });
 
     // zero + unit to zero
-    replace(/(\s|:)0(px|em|ex|cm|mm|in|pt|pc|%)/g, '$1' + '0');
+    replace(/(\s|:|,)0(px|em|ex|cm|mm|in|pt|pc|%)/g, '$1' + '0');
+    replace(/rect\(0(px|em|ex|cm|mm|in|pt|pc|%)/g, 'rect(0');
 
     // none to 0
     replace(/(border|border-top|border-right|border-bottom|border-left|outline):none/g, '$1:0');
@@ -150,9 +151,12 @@ var CleanCSS = {
     replace(/(background):none([;}])/g, '$1:0$2');
 
     // multiple zeros into one
-    replace(/0 0 0 0([^\.])/g, '0$1');
+    replace(/:0 0 0 0([^\.])/g, ':0$1');
     replace(/([: ,=\-])0\.(\d)/g, '$1.$2');
 
+    // restore rect(...) zeros syntax for 4 zeros
+    replace(/rect\(\s?0(\s|,)0[ ,]0[ ,]0\s?\)/g, 'rect(0$10$10$10)');
+
     // empty elements
     if (options.removeEmpty)
       replace(/[^}]+?{\s*?}/g, '');
diff --git a/test/unit-test.js b/test/unit-test.js
index d97242d81..67df3d007 100644
--- a/test/unit-test.js
+++ b/test/unit-test.js
@@ -229,6 +229,27 @@ vows.describe('clean-units').addBatch({
     'multiple zeros with fractions #2': [
       'div{padding:0 0 0 .5em}',
       'div{padding:0 0 0 .5em}'
+    ],
+    'rect zeros #1': 'div{clip:rect(0 0 0 0)}',
+    'rect zeros #2': [
+      'div{clip:rect(0px 0px 0px 0px)}',
+      'div{clip:rect(0 0 0 0)}'
+    ],
+    'rect zeros #3': [
+      'div{clip:rect( 0px 0px 0px 0px )}',
+      'div{clip:rect(0 0 0 0)}'
+    ],
+    'rect zeros #4': [
+      'div{clip:rect(0px, 0px, 0px, 0px)}',
+      'div{clip:rect(0,0,0,0)}'
+    ],
+    'rect zeros #5': [
+      'div{clip:rect(0.5% 0px 0px 0px)}',
+      'div{clip:rect(0.5% 0 0 0)}'
+    ],
+    'rect zeros #6': [
+      'div{clip:rect(0px 0px 0px 10px)}',
+      'div{clip:rect(0 0 0 10px)}'
     ]
   }),
   'floats': cssContext({