diff --git a/src/snek/static/chat-input.js b/src/snek/static/chat-input.js
index c1abd58..e2f15fe 100644
--- a/src/snek/static/chat-input.js
+++ b/src/snek/static/chat-input.js
@@ -217,8 +217,10 @@ class ChatInputComponent extends NjetComponent {
     const matches = this.matchMentionsToAuthors(mentions, authors);
     let updatedText = text;
     matches.forEach(({ mention, closestAuthor }) => {
-      const mentionRegex = new RegExp(`@${mention}`, 'g');
-      updatedText = updatedText.replace(mentionRegex, `@${closestAuthor}`);
+      if(closestAuthor){
+        const mentionRegex = new RegExp(`@${mention}`, 'g');
+        updatedText = updatedText.replace(mentionRegex, `@${closestAuthor}`);
+      }
     });
 
     return updatedText;