diff --git a/res/css/views/messages/_MessageActionBar.scss b/res/css/views/messages/_MessageActionBar.scss
index 81be6d1917d..e2fafe6c62a 100644
--- a/res/css/views/messages/_MessageActionBar.scss
+++ b/res/css/views/messages/_MessageActionBar.scss
@@ -80,7 +80,7 @@ limitations under the License.
     background-color: $secondary-fg-color;
 }
 
-.mx_MessageActionBar_maskButton:hover:after {
+.mx_MessageActionBar_maskButton:hover::after {
     background-color: $primary-fg-color;
 }