diff --git a/ext_tables.sql b/ext_tables.sql
index 8a434f2..6fa9454 100755
--- a/ext_tables.sql
+++ b/ext_tables.sql
@@ -14,7 +14,7 @@ CREATE TABLE tx_contacts_domain_model_contact (
     title varchar(255) DEFAULT '' NOT NULL,
     first_name varchar(255) DEFAULT '' NOT NULL,
     last_name varchar(255) DEFAULT '' NOT NULL,
-    birthday int(11) unsigned DEFAULT '0' NOT NULL,
+    birthday int(11) DEFAULT '0' NOT NULL,
 
     email varchar(255) DEFAULT '' NOT NULL,
     uri varchar(255) DEFAULT '' NOT NULL,