diff --git a/app/assets/stylesheets/desktop/compose.scss b/app/assets/stylesheets/desktop/compose.scss
index 546f35c34e..ddd914a98a 100644
--- a/app/assets/stylesheets/desktop/compose.scss
+++ b/app/assets/stylesheets/desktop/compose.scss
@@ -16,7 +16,9 @@
   }
 
   .item + #private-message-users {
-    width: 150px;
+    width: unset;
+    min-width: 150px;
+    flex: 1 1 auto;
   }
 
   .select-kit.is-expanded {