diff --git a/app/assets/stylesheets/common/base/topic-post.scss b/app/assets/stylesheets/common/base/topic-post.scss
index e228dd2dd77..9aebb72bd74 100644
--- a/app/assets/stylesheets/common/base/topic-post.scss
+++ b/app/assets/stylesheets/common/base/topic-post.scss
@@ -1349,6 +1349,8 @@ a.mention-group {
   display: flex;
   align-items: center;
   margin-right: 2em;
+  max-width: 400px;
+  overflow: hidden;
 
   img {
     margin: 0 0.25em;