diff --git a/tests/test_gc.py b/tests/test_gc.py
index e93a18c..12240b6 100644
--- a/tests/test_gc.py
+++ b/tests/test_gc.py
@@ -64,8 +64,7 @@ def test_use_nix(direnv_project: DirenvProject) -> None:
     direnv_project.setup_envrc("use nix")
     common_test(direnv_project)
 
-    # --pure here is just a way to make sure the environment changes
-    direnv_project.setup_envrc("use nix --pure")
+    direnv_project.setup_envrc("use nix --argstr 'echo Executing hijacked shellHook.'")
     common_test_clean(direnv_project)
 
 
@@ -81,7 +80,6 @@ def test_use_flake(direnv_project: DirenvProject) -> None:
     for symlink in inputs:
         assert symlink.is_dir()
 
-    # --impure here is just a way to make sure the environment changes
     direnv_project.setup_envrc("use flake --impure")
     common_test_clean(direnv_project)
 
diff --git a/tests/testenv/shell.nix b/tests/testenv/shell.nix
index c5c9d85..05d0a7a 100644
--- a/tests/testenv/shell.nix
+++ b/tests/testenv/shell.nix
@@ -1,14 +1,11 @@
-{ pkgs ? import <nixpkgs> {}, someArg ? null }:
+{ pkgs ? import <nixpkgs> { }, someArg ? null, shellHook ? ''
+  echo "Executing shellHook."
+'' }:
 pkgs.mkShellNoCC {
+  inherit shellHook;
+
   nativeBuildInputs = [ pkgs.hello ];
-  shellHook = ''
-    echo "Executing shellHook."
-  '';
   SHOULD_BE_SET = someArg;
 
-  passthru = {
-    subshell = pkgs.mkShellNoCC {
-      THIS_IS_A_SUBSHELL = "OK";
-    };
-  };
+  passthru = { subshell = pkgs.mkShellNoCC { THIS_IS_A_SUBSHELL = "OK"; }; };
 }