diff --git a/account/src/main/resources/org/killbill/billing/account/ddl.sql b/account/src/main/resources/org/killbill/billing/account/ddl.sql
index 195eb5b..5fa0931 100644
--- a/account/src/main/resources/org/killbill/billing/account/ddl.sql
+++ b/account/src/main/resources/org/killbill/billing/account/ddl.sql
@@ -4,7 +4,7 @@ DROP TABLE IF EXISTS accounts;
CREATE TABLE accounts (
record_id serial unique,
id varchar(36) NOT NULL,
- external_key varchar(255) NULL,
+ external_key varchar(255) NOT NULL,
email varchar(128) DEFAULT NULL,
name varchar(100) DEFAULT NULL,
first_name_length int DEFAULT NULL,
@@ -46,7 +46,7 @@ CREATE TABLE account_history (
record_id serial unique,
id varchar(36) NOT NULL,
target_record_id bigint /*! unsigned */ not null,
- external_key varchar(255) NULL,
+ external_key varchar(255) NOT NULL,
email varchar(128) DEFAULT NULL,
name varchar(100) DEFAULT NULL,
first_name_length int DEFAULT NULL,
diff --git a/account/src/main/resources/org/killbill/billing/account/migration/V20170915165117__external_key_not_null.sql b/account/src/main/resources/org/killbill/billing/account/migration/V20170915165117__external_key_not_null.sql
new file mode 100644
index 0000000..73b42fd
--- /dev/null
+++ b/account/src/main/resources/org/killbill/billing/account/migration/V20170915165117__external_key_not_null.sql
@@ -0,0 +1,2 @@
+alter table accounts modify external_key varchar(255) NOT NULL;
+alter table account_history modify external_key varchar(255) NOT NULL;