1 files changed, 10 insertions, 8 deletions
diff --git a/nixpkgs/nixos/lib/testing/nodes.nix b/nixpkgs/nixos/lib/testing/nodes.nix
index f58759b4cdba..a47d1c98ecec 100644
--- a/nixpkgs/nixos/lib/testing/nodes.nix
+++ b/nixpkgs/nixos/lib/testing/nodes.nix
@@ -28,15 +28,17 @@ let
             {
               virtualisation.qemu.package = testModuleArgs.config.qemu.package;
             })
-          (optionalAttrs (!config.node.pkgsReadOnly) {
+          ({ options, ... }: {
             key = "nodes.nix-pkgs";
-            config = {
-              # Ensure we do not use aliases. Ideally this is only set
-              # when the test framework is used by Nixpkgs NixOS tests.
-              nixpkgs.config.allowAliases = false;
-              # TODO: switch to nixpkgs.hostPlatform and make sure containers-imperative test still evaluates.
-              nixpkgs.system = hostPkgs.stdenv.hostPlatform.system;
-            };
+            config = optionalAttrs (!config.node.pkgsReadOnly) (
+              mkIf (!options.nixpkgs.pkgs.isDefined) {
+                # Ensure we do not use aliases. Ideally this is only set
+                # when the test framework is used by Nixpkgs NixOS tests.
+                nixpkgs.config.allowAliases = false;
+                # TODO: switch to nixpkgs.hostPlatform and make sure containers-imperative test still evaluates.
+                nixpkgs.system = hostPkgs.stdenv.hostPlatform.system;
+              }
+            );
           })
           testModuleArgs.config.extraBaseModules
         ];