diff --git a/compose.yml b/compose.yml
index da441a5..f74d910 100644
--- a/compose.yml
+++ b/compose.yml
@@ -114,6 +114,7 @@ services:
       POSTGRES_USER: matrix # FIXME: use different username+passwords for synapse & MAS DBs.
       POSTGRES_PASSWORD_FILE: /run/secrets/postgres_password
       POSTGRES_INITDB_ARGS: --encoding=UTF8 --locale=C
+      PGDATA: /var/lib/postgresql/data/data # otherwise it clashes with .gitkeep in the parent dir
     secrets:
       - postgres_password
     healthcheck: