diff --git a/db/migrate/20151221105330_add_categories_proposal.rb b/db/migrate/20151221105330_add_categories_proposal.rb
new file mode 100644
index 0000000..0a594e9
--- /dev/null
+++ b/db/migrate/20151221105330_add_categories_proposal.rb
@@ -0,0 +1,13 @@
+class AddCategoriesProposal < ActiveRecord::Migration
+
+  def self.up
+    ProposalsDiscussionPlugin::Proposal.find_each do |proposal|
+      proposal.inherit_parent_categories
+    end
+  end
+
+  def self.down
+    puts "Warning: cannot restore original categories"
+  end
+
+end
--
libgit2 0.21.2