diff --git a/enrol/authorize/db/postgres7.sql b/enrol/authorize/db/postgres7.sql
index 44d5f61c032..91398f80ab2 100644
--- a/enrol/authorize/db/postgres7.sql
+++ b/enrol/authorize/db/postgres7.sql
@@ -8,7 +8,7 @@ CREATE TABLE prefix_enrol_authorize (
     status integer DEFAULT 0 NOT NULL,
     timecreated integer DEFAULT 0 NOT NULL,
     settletime integer DEFAULT 0 NOT NULL,
-    amount varchar(10) DEFAULT '0',
+    amount varchar(10) DEFAULT '0' NOT NULL,
     currency varchar(3) DEFAULT 'USD' NOT NULL
 );