diff --git a/res/css/views/rooms/_MessageComposer.scss b/res/css/views/rooms/_MessageComposer.scss
index c24e4912d4..2789ffdfb7 100644
--- a/res/css/views/rooms/_MessageComposer.scss
+++ b/res/css/views/rooms/_MessageComposer.scss
@@ -256,7 +256,7 @@ limitations under the License.
     border-radius: 100%;
     background-color: $button-bg-color;
 
-    &:before {
+    &::before {
         position: absolute;
         height: 16px;
         width: 16px;