diff --git a/server/migrations/018_comment_parent_cascade.down.sql b/server/migrations/018_comment_parent_cascade.down.sql
new file mode 100644
index 00000000..ef56c144
--- /dev/null
+++ b/server/migrations/018_comment_parent_cascade.down.sql
@@ -0,0 +1,3 @@
+ALTER TABLE comment DROP CONSTRAINT IF EXISTS comment_parent_id_fkey;
+ALTER TABLE comment ADD CONSTRAINT comment_parent_id_fkey
+    FOREIGN KEY (parent_id) REFERENCES comment(id) ON DELETE SET NULL;
diff --git a/server/migrations/018_comment_parent_cascade.up.sql b/server/migrations/018_comment_parent_cascade.up.sql
new file mode 100644
index 00000000..986e6863
--- /dev/null
+++ b/server/migrations/018_comment_parent_cascade.up.sql
@@ -0,0 +1,3 @@
+ALTER TABLE comment DROP CONSTRAINT IF EXISTS comment_parent_id_fkey;
+ALTER TABLE comment ADD CONSTRAINT comment_parent_id_fkey
+    FOREIGN KEY (parent_id) REFERENCES comment(id) ON DELETE CASCADE;