diff --git a/js/show-own-posts.js b/js/show-own-posts.js
index 22660d82..18032f3e 100644
--- a/js/show-own-posts.js
+++ b/js/show-own-posts.js
@@ -47,7 +47,7 @@ var update_own = function() {
     else
       return;
 
-    if (posts[board].indexOf(postID) !== -1) {
+    if (posts[board] && posts[board].indexOf(postID) !== -1) {
       $(this).after(' <small>'+_('(You)')+'</small>');
     }
   });