diff --git a/setuptools/tests/fixtures.py b/setuptools/tests/fixtures.py
index 629daf93d..9204d1f80 100644
--- a/setuptools/tests/fixtures.py
+++ b/setuptools/tests/fixtures.py
@@ -82,6 +82,7 @@ def setuptools_sdist(tmp_path_factory, request):
             "-m",
             "build",
             "--sdist",
+            "--no-isolation",
             "--outdir",
             str(tmp),
             str(request.config.rootdir),
@@ -107,6 +108,7 @@ def setuptools_wheel(tmp_path_factory, request):
             "-m",
             "build",
             "--wheel",
+            "--no-isolation",
             "--outdir",
             str(tmp),
             str(request.config.rootdir),