diff --git a/elements.less b/elements.less
index e0a3fb5..82de80f 100644
--- a/elements.less
+++ b/elements.less
@@ -72,9 +72,18 @@
   -moz-background-clip: padding; -webkit-background-clip: padding-box; background-clip: padding-box; 
 }
 .opacity(@opacity: 0.5) {
+  @percent: @opacity * 100;
+  /* IE 8 */
+  -ms-filter: ~"progid:DXImageTransform.Microsoft.Alpha(opacity=(@{percentage}))";
+  /* IE 5-7 */ 
+  filter: ~"alpha(opacity = (@{percentage}))";
+  /* Netscape */
   -moz-opacity: @opacity;
+  /* Safari 1.x */
   -khtml-opacity: @opacity;
+  /* Webkit */
   -webkit-opacity: @opacity;
+  /* Good browsers */
   opacity: @opacity;
 }
 .transition-duration(@duration: 0.2s) {