diff --git a/nixos/system-tests.nix b/nixos/system-tests.nix
index b2556d4692ee0c3eff96554fa7c13df59ec94507..5f51d01dd57267b75b3742c76c03c1393676d426 100644
--- a/nixos/system-tests.nix
+++ b/nixos/system-tests.nix
@@ -1,6 +1,6 @@
 # The overall system test suite for PrivateStorageio NixOS configuration.
 let
-  pkgs = import <nixpkgs> { };
+  pkgs = import ../nixpkgs-ps.nix { };
 in {
   private-storage = pkgs.nixosTest ./modules/tests/private-storage.nix;
   tahoe = pkgs.nixosTest ./modules/tests/tahoe.nix;