diff --git a/app/models/issue_query.rb b/app/models/issue_query.rb
index c911510..c0a0fec 100644
--- a/app/models/issue_query.rb
+++ b/app/models/issue_query.rb
@@ -206,6 +206,7 @@ class IssueQuery < Query
         :values => categories.collect{|s| [s.name, s.id.to_s] }
     end
 
+    add_available_filter 'parent_id', :type => :integer, :label => 'field_parent_issue'
     add_available_filter "subject", :type => :text
     add_available_filter "created_on", :type => :date_past
     add_available_filter "updated_on", :type => :date_past