diff --git a/views/mixins/catalogtile.pug b/views/mixins/catalogtile.pug
index 9ca4ed2f..2516671e 100644
--- a/views/mixins/catalogtile.pug
+++ b/views/mixins/catalogtile.pug
@@ -13,7 +13,7 @@ mixin catalogtile(post, index, overboard=false)
 		data-name=post.name
 		data-tripcode=post.tripcode
 		data-subject=post.subject
-		data-filter=((post.subject+post.nomarkup).toLowerCase() || '')
+		data-filter=((post.subject||'')+(post.nomarkup||'')).toLowerCase()
 		data-date=post.date
 		data-replies=post.replyposts
 		data-bump=post.bumped)