diff --git a/src/com/yahoo/platform/yui/compressor/CssCompressor.java b/src/com/yahoo/platform/yui/compressor/CssCompressor.java
index 8a5cfe93..2e08ec61 100644
--- a/src/com/yahoo/platform/yui/compressor/CssCompressor.java
+++ b/src/com/yahoo/platform/yui/compressor/CssCompressor.java
@@ -338,7 +338,7 @@ public void compress(Writer out, int linebreakpos)
         } while (!(css.equals(oldCss)));
 
         // Replace 0(px,em,%) with 0 inside groups (e.g. -MOZ-RADIAL-GRADIENT(CENTER 45DEG, CIRCLE CLOSEST-SIDE, ORANGE 0%, RED 100%))
-        p = Pattern.compile("(?i)\\( ?((?:[0-9a-z-.]+[ ,])*)?(?:0?\\.)?0(?:px|em|%|in|cm|mm|pc|pt|ex|deg|g?rad|m?s|k?hz)");
+        p = Pattern.compile("(?i)\\( ?((?:[#0-9a-z-.]+[ ,])*)?(?:0?\\.)?0(?:px|em|%|in|cm|mm|pc|pt|ex|deg|g?rad|m?s|k?hz)");
         do {
           oldCss = css;
           m = p.matcher(css);
@@ -353,6 +353,12 @@ public void compress(Writer out, int linebreakpos)
         css = css.replaceAll(":0 0 0(;|})", ":0$1");
         css = css.replaceAll(":0 0(;|})", ":0$1");
 
+        // Replace "from" with "0%" in keyframes
+        css = css.replaceAll("([{},])from([{,])", "$10%$2");
+
+        // Replace "100%" with "to" in keyframes
+        css = css.replaceAll("([{},])100%([{,])", "$1to$2");
+
 
         // Replace background-position:0; with background-position:0 0;
         // same for transform-origin
diff --git a/tests/background-gradient.css b/tests/background-gradient.css
new file mode 100644
index 00000000..adf28e17
--- /dev/null
+++ b/tests/background-gradient.css
@@ -0,0 +1,10 @@
+.gradient {
+    background: #ffffff;
+    background: -moz-linear-gradient(top, #ffffff 0%, #f1f1f1 50%, #e1e1e1 51%, #f6f6f6 100%);
+    background: -webkit-gradient(linear, left top, left bottom, color-stop(0%,#ffffff), color-stop(50%,#f1f1f1), color-stop(51%,#e1e1e1), color-stop(100%,#f6f6f6));
+    background: -webkit-linear-gradient(top, #ffffff 0%,#f1f1f1 50%,#e1e1e1 51%,#f6f6f6 100%);
+    background: -o-linear-gradient(top, #ffffff 0%,#f1f1f1 50%,#e1e1e1 51%,#f6f6f6 100%);
+    background: -ms-linear-gradient(top, #ffffff 0%,#f1f1f1 50%,#e1e1e1 51%,#f6f6f6 100%);
+    background: linear-gradient(to bottom, #ffffff 0%,#f1f1f1 50%,#e1e1e1 51%,#f6f6f6 100%);
+    filter: progid:DXImageTransform.Microsoft.gradient( startColorstr='#ffffff', endColorstr='#f6f6f6',GradientType=0 );
+}
\ No newline at end of file
diff --git a/tests/background-gradient.css.min b/tests/background-gradient.css.min
new file mode 100644
index 00000000..2dcb3380
--- /dev/null
+++ b/tests/background-gradient.css.min
@@ -0,0 +1 @@
+.gradient{background:#fff;background:-moz-linear-gradient(top,#fff 0,#f1f1f1 50%,#e1e1e1 51%,#f6f6f6 100%);background:-webkit-gradient(linear,left top,left bottom,color-stop(0,#fff),color-stop(50%,#f1f1f1),color-stop(51%,#e1e1e1),color-stop(100%,#f6f6f6));background:-webkit-linear-gradient(top,#fff 0,#f1f1f1 50%,#e1e1e1 51%,#f6f6f6 100%);background:-o-linear-gradient(top,#fff 0,#f1f1f1 50%,#e1e1e1 51%,#f6f6f6 100%);background:-ms-linear-gradient(top,#fff 0,#f1f1f1 50%,#e1e1e1 51%,#f6f6f6 100%);background:linear-gradient(to bottom,#fff 0,#f1f1f1 50%,#e1e1e1 51%,#f6f6f6 100%);filter:progid:DXImageTransform.Microsoft.gradient(startColorstr='#ffffff',endColorstr='#f6f6f6',GradientType=0)}
\ No newline at end of file
diff --git a/tests/issue151.css.min b/tests/issue151.css.min
index 00f934fb..de0e10c8 100644
--- a/tests/issue151.css.min
+++ b/tests/issue151.css.min
@@ -1 +1 @@
-@keyframes fadeIn{0%{opacity:0}100%{opacity:1}}
+@keyframes fadeIn{0%{opacity:0}to{opacity:1}}
diff --git a/tests/keyframes.css b/tests/keyframes.css
new file mode 100644
index 00000000..a2dfc218
--- /dev/null
+++ b/tests/keyframes.css
@@ -0,0 +1,86 @@
+/*
+ * /(?<!keyframes)\s+/  -> ''
+ * /\/\*.*?\*\//        -> ''
+ * ';}'                 -> '}'
+ * 'from'               -> '0%'
+ * '100%'               -> 'to'
+ */
+
+/* steps defined by strings */
+@keyframes test1-1 {
+    from {
+        opacity: 1;
+    }
+    to {
+        opacity: 0;
+    }
+}
+@keyframes test1-2 {
+    to {
+        opacity: 0;
+    }
+    from {
+        opacity: 1;
+    }
+}
+
+/* steps defined by percentage */
+@keyframes test2 {
+    0% {
+        opacity: 1;
+    }
+    50% {
+        opacity: 0.9;
+    }
+}
+
+/* steps defined by percentage and strings */
+@keyframes test3 {
+    from {
+        opacity: 1;
+    }
+    50% {
+        opacity: 0.9;
+    }
+    to {
+        opacity: 0.5;
+    }
+}
+
+/* same value for multiple steps */
+@keyframes test4-1 {
+    50%, 0%, to {
+        opacity: 0;
+    }
+    25%, 75% {
+        opacity: 1;
+    }
+}
+@keyframes test4-2 {
+    50%, from, to {
+        opacity: 0;
+    }
+    25%, 75% {
+        opacity: 1;
+    }
+}
+
+/* percent only steps, mixed order */
+@keyframes test5 {
+    100% {
+        opacity: 0;
+    }
+    0% {
+        opacity: 1;
+    }
+}
+
+/* vendor prefixed */
+@-webkit-keyframes test6 {
+    0%, 50% {
+        opacity: 1;
+    }
+    100% {
+        opacity: 0;
+    }
+}
\ No newline at end of file
diff --git a/tests/keyframes.css.min b/tests/keyframes.css.min
new file mode 100644
index 00000000..b17a3209
--- /dev/null
+++ b/tests/keyframes.css.min
@@ -0,0 +1 @@
+@keyframes test1-1{0%{opacity:1}to{opacity:0}}@keyframes test1-2{to{opacity:0}0%{opacity:1}}@keyframes test2{0%{opacity:1}50%{opacity:.9}}@keyframes test3{0%{opacity:1}50%{opacity:.9}to{opacity:.5}}@keyframes test4-1{50%,0%,to{opacity:0}25%,75%{opacity:1}}@keyframes test4-2{50%,0%,to{opacity:0}25%,75%{opacity:1}}@keyframes test5{to{opacity:0}0%{opacity:1}}@-webkit-keyframes test6{0%,50%{opacity:1}to{opacity:0}}
\ No newline at end of file