diff --git a/migrations/kind_2_down.sql b/migrations/kind_2_down.sql
index 6b19cea..14bbf89 100644
--- a/migrations/kind_2_down.sql
+++ b/migrations/kind_2_down.sql
@@ -1,3 +1,6 @@
-DELETE FROM kind WHERE id = 'r';
-DELETE FROM kind WHERE id = 'c';
-DELETE FROM kind WHERE id = 'a';
+DELETE FROM kind WHERE id IN (
+	'x',
+	'r',
+	'c',
+	'a'
+);
diff --git a/migrations/kind_2_up.sql b/migrations/kind_2_up.sql
index e54eee7..cbae761 100644
--- a/migrations/kind_2_up.sql
+++ b/migrations/kind_2_up.sql
@@ -1,3 +1,4 @@
 INSERT INTO kind(id, name) VALUES ('a', 'author');
 INSERT INTO kind(id, name) VALUES ('c', 'character');
 INSERT INTO kind(id, name) VALUES ('r', 'release');
+INSERT INTO kind(id, name) VALUES ('x', 'extension');