diff --git a/modules/services/databases/postgresql.nix b/modules/services/databases/postgresql.nix
index 5054ca8a792..8185f3866ba 100644
--- a/modules/services/databases/postgresql.nix
+++ b/modules/services/databases/postgresql.nix
@@ -75,6 +75,7 @@ in
 
       dataDir = mkOption {
         default = "/var/db/postgresql-${cfg.package.psqlSchema}";
+        defaultText = "/var/db/postgresql-{version}";
         description = ''
           Data directory for PostgreSQL.
         '';