diff --git a/tests/functional2/build/test_fixed.py b/tests/functional2/build/test_fixed.py
index 734e2c1b2..4cedd7c1c 100644
--- a/tests/functional2/build/test_fixed.py
+++ b/tests/functional2/build/test_fixed.py
@@ -1,4 +1,3 @@
-import sys
 import re
 from pathlib import Path
 
@@ -24,7 +23,7 @@ def impure_vars(env: ManagedEnv):
 def test_bad(nix: Nix):
     res = nix.nix_instantiate(["fixed.nix", "-A", "good.0"], build=True).run().ok()
     store_path = nix.nix_store(["-q", res.stdout_plain], build=True).run().ok().stdout_plain
-    path = Path(f"{nix.env.dirs.test_root}{store_path}" if sys.platform != "darwin" else store_path)
+    path = Path(store_path)
     assert not path.exists()
 
     # Building with the bad hash should produce the "good" output path as
diff --git a/tests/functional2/lang/test_lang.py b/tests/functional2/lang/test_lang.py
index 4b0ee1a05..9939548a2 100644
--- a/tests/functional2/lang/test_lang.py
+++ b/tests/functional2/lang/test_lang.py
@@ -8,7 +8,7 @@ import yaml
 from _pytest.python import Metafunc
 
 from lang.lang_util import LangTest, fetch_all_lang_tests, LangTestRunner
-from testlib.fixtures.nix import Nix
+from testlib.fixtures.nix import Nix, with_diverted_store
 from testlib.fixtures.snapshot import Snapshot
 
 
@@ -92,6 +92,7 @@ def test_parse_fail(files: Path, nix: Nix, flags: list[str], snapshot: Callable[
     assert snapshot("err.exp") == stderr
 
 
+@with_diverted_store
 def test_eval_okay(files: Path, nix: Nix, flags: list[str], snapshot: Callable[[str], Snapshot]):
     nix_command = nix.nix_instantiate(["--eval", "--strict", *flags, files / "in.nix"], flake=True)
     result = nix_command.run().ok()
@@ -101,6 +102,7 @@ def test_eval_okay(files: Path, nix: Nix, flags: list[str], snapshot: Callable[[
     assert snapshot("err.exp") == stderr
 
 
+@with_diverted_store
 def test_eval_fail(files: Path, nix: Nix, flags: list[str], snapshot: Callable[[str], Snapshot]):
     nix_command = nix.nix_instantiate(
         ["--eval", "--strict", "--show-trace", *flags, files / "in.nix"], flake=True
diff --git a/tests/functional2/store/test_evil_nars.py b/tests/functional2/store/test_evil_nars.py
index aeaf68994..0a4984522 100644
--- a/tests/functional2/store/test_evil_nars.py
+++ b/tests/functional2/store/test_evil_nars.py
@@ -6,7 +6,7 @@ from pathlib import Path
 
 import pytest
 
-from testlib.fixtures.nix import Nix
+from testlib.fixtures.nix import Nix, with_diverted_store
 from testlib.nar import (
     DirectoryUnordered,
     NarItem,
@@ -102,6 +102,7 @@ EVIL_NARS: list[tuple[str, NarItem]] = [
 
 
 @pytest.mark.parametrize(("name", "nar"), EVIL_NARS, ids=next(zip(*EVIL_NARS)))
+@with_diverted_store
 def test_evil_nar(nix: Nix, name: str, nar: NarItem, logger: Logger):
     bio = BytesIO()
 
diff --git a/tests/functional2/store/test_http.py b/tests/functional2/store/test_http.py
index d27c68200..d88d50478 100644
--- a/tests/functional2/store/test_http.py
+++ b/tests/functional2/store/test_http.py
@@ -6,7 +6,7 @@ import pytest
 
 from testlib.fixtures.file_helper import File, with_files
 from testlib.fixtures.http_server import http_server
-from testlib.fixtures.nix import Nix
+from testlib.fixtures.nix import Nix, with_diverted_store
 
 
 class HTTPStore:
@@ -101,6 +101,7 @@ def nars_from_narinfo_cache(db_path: Path) -> list[dict[str, str | bool]]:
 
 
 @with_files({"test-file": File("hello world")})
+@with_diverted_store
 def test_http_simple(nix: Nix, store: HTTPStore, files: Path):
     test_file = files / "test-file"
     result = nix.nix(cmd=["store", "add-file", test_file], flake=True).run()
diff --git a/tests/functional2/testlib/fixtures/env.py b/tests/functional2/testlib/fixtures/env.py
index 1b016f7f5..b3e64d495 100644
--- a/tests/functional2/testlib/fixtures/env.py
+++ b/tests/functional2/testlib/fixtures/env.py
@@ -154,10 +154,6 @@ class _Dirs:
     tmpdir: Path | None
     """used for nar caching"""
     nix_store_dir: Path | None = None
-    """
-    store dir override for building on macos *specifically*. do not
-    use or set this for any other purpose or many tests will break.
-    """
 
     def get_env_keys(self) -> set[str]:
         return {f.name.upper() for f in dataclasses.fields(self)}
@@ -194,6 +190,7 @@ class ManagedEnv:
             nix_conf_dir=self._get_dir("etc/nix"),
             nix_bin_dir=lix_bin,
             real_store_dir=self._get_dir("nix/store"),
+            nix_store_dir=self._get_dir("nix/store"),
             cache_dir=self._get_dir("test-binary-cache"),
             xdg_cache_home=self._get_dir("test-home/.cache"),
             tmpdir=self._get_dir("tmp"),
diff --git a/tests/functional2/testlib/fixtures/nix.py b/tests/functional2/testlib/fixtures/nix.py
index 0afa7d8e0..ab210db3b 100644
--- a/tests/functional2/testlib/fixtures/nix.py
+++ b/tests/functional2/testlib/fixtures/nix.py
@@ -147,11 +147,19 @@ class Nix:
         if self._settings is None:
             self._settings = NixSettings()
             self._settings.store = f"local?root={self.env.dirs.test_root}"
+            if sys.platform == "linux":
+                # sandbox build dir cannot be withing store dir. choose a short non-overlapping path.
+                self._settings.sandbox_build_dir = (
+                    "/build-f2" if self.env.dirs.test_root.parts[1] != "build-f2" else "/build.f2"
+                )
 
         return self._settings
 
     def nix_cmd(
-        self, argv: list[str], flake: bool = False, build: bool | Literal["auto"] = "auto"
+        self,
+        argv: list[str],
+        flake: bool = False,
+        build: bool | Literal["auto"] = "auto",  # noqa: ARG002
     ) -> Command:
         """
         Constructs a NixCommand with the appropriate settings.
@@ -161,17 +169,6 @@ class Nix:
         settings = self.settings.clone()
         if flake:
             settings.add_xp_feature("nix-command", "flakes")
-        # FIXME(rootile): Darwin needs special handling here, as it does not support (non-root) chroots...
-        #  Hence, it cannot build using a relocated store so we just use the local (aka global) store instead
-        #  This is kinda ugly but what else can one do
-        if sys.platform == "darwin":
-            if build is True or (
-                # argv[1:2] does not throw a key error on empty lists
-                # hence not crashing this check on an empty `nix.nix([])` call
-                build == "auto" and (argv[0] == "nix-build" or argv[1:2] == ["build"])
-            ):
-                settings.store = None
-                self.env.dirs.nix_store_dir = self.env.dirs.real_store_dir
 
         settings.to_env_overlay(self.env)
         return Command(argv=argv, exe=self._nix_executable, _env=self.env)
@@ -352,3 +349,19 @@ def nix(tmp_path: Path, env: ManagedEnv, logger: logging.Logger) -> Generator[Ni
     # for pytest to be able to delete the files during cleanup
     cmd = Command(argv=["chmod", "-R", "+w", str(tmp_path.absolute())], _env=env)
     cmd.run().ok()
+
+
+@pytest.fixture
+def enable_diverted_store(nix: Nix):
+    """
+    clear NIX_STORE_DIR, resetting it to the default (ie /nix/store).
+    this makes builds impossible on platforms that cannot bind-mount,
+    (e.g. macos) but it is important for eval result reproducibility.
+    while builds may not work, substitution should still be possible.
+    """
+    nix.env.dirs.nix_store_dir = None
+    nix.settings.sandbox_build_dir = None
+
+
+def with_diverted_store(func: Callable[[Any], None]) -> Callable[[Any], None]:
+    return pytest.mark.usefixtures("enable_diverted_store")(func)
diff --git a/tests/functional2/testlib/fixtures/test_env.py b/tests/functional2/testlib/fixtures/test_env.py
index 9ede7c9c4..53e998d61 100644
--- a/tests/functional2/testlib/fixtures/test_env.py
+++ b/tests/functional2/testlib/fixtures/test_env.py
@@ -98,13 +98,7 @@ def test_env_dirs_created(env: ManagedEnv):
     fields = dataclasses.asdict(env.dirs).items()
     assert len(fields) > 1
     for name, field in fields:
-        field: Path | None
-        # we never want to set NIX_STORE_DIR on linux due to unfortunate config ordering.
-        # creating a fresh env should always have it unset, it'll only be set when needed
-        if name == "nix_store_dir":
-            assert field is None
-        else:
-            field.exists()
+        field.exists()
 
 
 def test_env_get_path_fails(env: ManagedEnv):
@@ -129,6 +123,7 @@ def test_env_to_env(tmp_path: Path):
         "NIX_STATE_DIR",
         "NIX_CONF_DIR",
         "NIX_BIN_DIR",
+        "NIX_STORE_DIR",
         "REAL_STORE_DIR",
         "CACHE_DIR",
         "XDG_CACHE_HOME",