diff --git a/lib.nix b/lib.nix
index 3b7b9c0..7c3570a 100644
--- a/lib.nix
+++ b/lib.nix
@@ -142,11 +142,12 @@ in
         name = "run-postgres";
         text = ''
           set -euo pipefail
+          mkdir -p ${lib.escapeShellArg runtimeDir}
+
           PGDATA=$(realpath ${data_dir})
           PGHOST=$(realpath ${runtimeDir})
           PGPORT=${builtins.toString port}
           export PGDATA PGHOST PGPORT
-          mkdir -p ${lib.escapeShellArg runtimeDir}
           ${setupScript}/bin/setup-postgres
           ${package}/bin/postgres
         '';