diff --git a/app/models/post_version.rb b/app/models/post_version.rb
index 885cb40f0..34d35cac0 100644
--- a/app/models/post_version.rb
+++ b/app/models/post_version.rb
@@ -151,7 +151,7 @@ class PostVersion < ApplicationRecord
   end
 
   def pretty_rating
-    Post::RATINGS.fetch(rating)
+    Post::RATINGS[rating] # XXX some old post versions have nil ratings.
   end
 
   def changes