diff --git a/core/themes/bartik/css/components/form.css b/core/themes/bartik/css/components/form.css
index 82377ad..6d15066 100644
--- a/core/themes/bartik/css/components/form.css
+++ b/core/themes/bartik/css/components/form.css
@@ -152,7 +152,6 @@ input.form-submit:focus {
 .image-button-disabled:hover,
 .image-button-disabled:active,
 .image-button-disabled:focus {
-  -ms-filter:"progid:DXImageTransform.Microsoft.Alpha(Opacity=50)";
   filter: alpha(opacity=50);
   opacity: .5;
 }