diff --git a/synapse/storage/schema/delta/48/groups_joinable.sql b/synapse/storage/schema/delta/48/groups_joinable.sql
index 9e106e909c..ace7d0a723 100644
--- a/synapse/storage/schema/delta/48/groups_joinable.sql
+++ b/synapse/storage/schema/delta/48/groups_joinable.sql
@@ -13,4 +13,4 @@
  * limitations under the License.
  */
 
-ALTER TABLE groups ADD COLUMN is_joinable BOOL DEFAULT 0 NOT NULL;
+ALTER TABLE groups ADD COLUMN is_joinable SMALLINT DEFAULT 0 NOT NULL;