diff --git a/cibuildwheel/macos.py b/cibuildwheel/macos.py
index 1344c9ff..3bd0df79 100644
--- a/cibuildwheel/macos.py
+++ b/cibuildwheel/macos.py
@@ -92,7 +92,7 @@ def build(project_dir, output_dir, test_command, test_requires, test_extras, bef
         call(['python', '--version'], env=env)
 
         # install pip & wheel
-        call(['python', get_pip_script, '--no-setuptools', '--no-wheel'], env=env)
+        call(['python', get_pip_script, '--no-setuptools', '--no-wheel'], env=env, cwd="/tmp")
         assert os.path.exists(os.path.join(installation_bin_path, 'pip'))
         call(['pip', '--version'], env=env)
         call(['pip', 'install', '--upgrade', 'setuptools', 'wheel', 'delocate'], env=env)
diff --git a/cibuildwheel/windows.py b/cibuildwheel/windows.py
index e5d3240d..7c03f815 100644
--- a/cibuildwheel/windows.py
+++ b/cibuildwheel/windows.py
@@ -124,7 +124,7 @@ def build(project_dir, output_dir, test_command, test_requires, test_extras, bef
 
         # make sure pip is installed
         if not os.path.exists(os.path.join(config_python_path, 'Scripts', 'pip.exe')):
-            simple_shell(['python', get_pip_script], env=env)
+            simple_shell(['python', get_pip_script], env=env, cwd="C:\\cibw")
         assert os.path.exists(os.path.join(config_python_path, 'Scripts', 'pip.exe'))
 
         # prepare the Python environment