diff --git a/script/sql/create/4.tanks.sql b/script/sql/create/4.tanks.sql
index b15c29f..20f3e0c 100644
--- a/script/sql/create/4.tanks.sql
+++ b/script/sql/create/4.tanks.sql
@@ -1,6 +1,6 @@
 -- [TANKS]
 
-create type tanks_overflow as enum ('yes', 'no');
+create type tanks_overflow as enum ('YES', 'NO');
 
 create table tanks
 (