diff --git a/static/styles/zulip.scss b/static/styles/zulip.scss
index 84c61b0a3a..509af1b0e2 100644
--- a/static/styles/zulip.scss
+++ b/static/styles/zulip.scss
@@ -1545,6 +1545,10 @@ blockquote p {
     vertical-align: top;
     border-radius: 4px;
     overflow: hidden;
+
+    &.guest-avatar::after {
+        outline: 2px solid hsl(0, 0%, 100%);
+    }
 }
 
 .home-error-bar {
diff --git a/static/templates/single_message.handlebars b/static/templates/single_message.handlebars
index b189c6db08..1d25ea1739 100644
--- a/static/templates/single_message.handlebars
+++ b/static/templates/single_message.handlebars
@@ -10,8 +10,8 @@
                     <span class="message_sender{{^status_message}} sender_info_hover{{/status_message}} no-select">
                         {{#include_sender}}
                             {{! See ../js/notifications.js for another user of avatar_url. }}
-                            <div class="u-{{msg/sender_id}} inline_profile_picture{{#status_message}} sender_info_hover{{/status_message}}" aria-hidden="true">
-                                <img src="{{small_avatar_url}}" alt="" class="no-drag{{#if sender_is_guest}} guest_user_avatar{{/if}}"/>
+                            <div class="u-{{msg/sender_id}} inline_profile_picture{{#status_message}} sender_info_hover{{/status_message}}{{#sender_is_guest}} guest-avatar{{/sender_is_guest}}" aria-hidden="true">
+                                <img src="{{small_avatar_url}}" alt="" class="no-drag"/>
                             </div>
                             {{#if status_message}}
                                 <span class="sender-status">