diff --git a/tests/functional2/testlib/fixtures/nix.py b/tests/functional2/testlib/fixtures/nix.py
index dcaa9eec4..fead593c4 100644
--- a/tests/functional2/testlib/fixtures/nix.py
+++ b/tests/functional2/testlib/fixtures/nix.py
@@ -480,6 +480,15 @@ def pytest_generate_tests(metafunc: pytest.Metafunc):
         metafunc.parametrize("nix", protocols, indirect=True, ids=ids)
 
 
+@pytest.fixture
+def fake_nixpkgs(nix: Nix):
+    nixpkgs = nix.env.dirs.test_root / "nixpkgs"
+    nixpkgs.mkdir()
+    (nixpkgs / "default.nix").write_text('{...}: {lib.version = "f2-fake-nixpkgs";}')
+
+    nix.env["NIX_PATH"] = f"nixpkgs={nixpkgs.absolute()}"
+
+
 @pytest.fixture
 def enable_diverted_store(nix: Nix):
     """