diff --git a/app/models/issue.rb b/app/models/issue.rb
index e0f93fa..4f3b463 100644
--- a/app/models/issue.rb
+++ b/app/models/issue.rb
@@ -1202,6 +1202,7 @@ class Issue < ActiveRecord::Base
   # Returns a string of css classes that apply to the issue
   def css_classes(user=User.current)
     s = "issue tracker-#{tracker_id} status-#{status_id} #{priority.try(:css_classes)}"
+    s << " category-#{category_id}" if category.present?
     s << ' closed' if closed?
     s << ' overdue' if overdue?
     s << ' child' if child?