diff --git a/db/migrate/20230526181715_backfill_missing_created_at_on_commented_notifications.rb b/db/migrate/20230526181715_backfill_missing_created_at_on_commented_notifications.rb
new file mode 100644
index 00000000..906b6859
--- /dev/null
+++ b/db/migrate/20230526181715_backfill_missing_created_at_on_commented_notifications.rb
@@ -0,0 +1,17 @@
+# frozen_string_literal: true
+
+class BackfillMissingCreatedAtOnCommentedNotifications < ActiveRecord::Migration[6.1]
+  def up
+    execute <<~SQUIRREL
+      UPDATE notifications
+      SET created_at = comments.created_at, updated_at = comments.created_at
+      FROM comments
+      WHERE notifications.target_id = comments.id AND notifications.created_at IS NULL AND notifications.type = 'Notification::Commented'
+    SQUIRREL
+
+    # clean up notifications for deleted comments
+    Notification::Commented.where(created_at: nil).destroy_all
+  end
+
+  def down; end
+end
diff --git a/db/schema.rb b/db/schema.rb
index 39dc6424..c45fb69c 100644
--- a/db/schema.rb
+++ b/db/schema.rb
@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 2023_02_27_174822) do
+ActiveRecord::Schema.define(version: 2023_05_26_181715) do
 
   # These are extensions that must be enabled in order to support this database
   enable_extension "plpgsql"