diff --git a/extras/migrations/009-db-mapping-add-selector.migration b/extras/migrations/009-db-mapping-add-selector.migration
index 23e311b06d2917ffe5bc5a5b1302e9a53feb319c..21b918f65c740fd9a5c96080f5938f0aa2d9b144 100755
--- a/extras/migrations/009-db-mapping-add-selector.migration
+++ b/extras/migrations/009-db-mapping-add-selector.migration
@@ -40,7 +40,7 @@ def migrate():
     cursor.execute("""
     ALTER TABLE Mapping
         ADD COLUMN selector varchar(255) DEFAULT NULL AFTER version,
-        ADD COLUMN selector_version unsigned DEFAULT NULL AFTER selector;""")
+        ADD COLUMN selector_version smallint(6) DEFAULT NULL AFTER selector;""")
     connection.commit()
     connection.close()
     migration.info('Added column hg18.Mapping.selector')
@@ -51,7 +51,7 @@ def migrate():
     cursor.execute("""
     ALTER TABLE Mapping
         ADD COLUMN selector varchar(255) DEFAULT NULL AFTER version,
-        ADD COLUMN selector_version unsigned DEFAULT NULL AFTER selector;""")
+        ADD COLUMN selector_version smallint(6) DEFAULT NULL AFTER selector;""")
     connection.commit()
     connection.close()
     migration.info('Added column hg19.Mapping.selector')
diff --git a/extras/post-install.sh b/extras/post-install.sh
index 4e173c485bd8b842aeae3860936ebd859d94b458..0103866511708e77460e27ef9d78ec3a3eba3fad 100644
--- a/extras/post-install.sh
+++ b/extras/post-install.sh
@@ -105,7 +105,7 @@ CREATE TABLE Mapping (
   transcript varchar(20) NOT NULL DEFAULT '',
   version smallint(6) DEFAULT NULL,
   selector varchar(255) DEFAULT NULL,
-  selector_version unsigned DEFAULT NULL,
+  selector_version smallint(6) DEFAULT NULL,
   chromosome varchar(40) DEFAULT NULL,
   orientation char(1) DEFAULT NULL,
   start int(11) unsigned DEFAULT NULL,
@@ -171,7 +171,7 @@ CREATE TABLE Mapping (
   transcript varchar(20) NOT NULL DEFAULT '',
   version smallint(6) DEFAULT NULL,
   selector varchar(255) DEFAULT NULL,
-  selector_version unsigned DEFAULT NULL,
+  selector_version smallint(6) DEFAULT NULL,
   chromosome varchar(40) DEFAULT NULL,
   orientation char(1) DEFAULT NULL,
   start int(11) unsigned DEFAULT NULL,