diff --git a/postgres/defaults.yaml b/postgres/defaults.yaml
index e737366..2e17dd8 100644
--- a/postgres/defaults.yaml
+++ b/postgres/defaults.yaml
@@ -21,7 +21,7 @@ postgres:
     env: []
 
   conf_dir: /var/lib/pgsql/data
-  conf_dir_mode: 0775
+  conf_dir_mode: '0775'
   postgresconf: ""
 
   macos: