diff --git a/cibuildwheel/linux.py b/cibuildwheel/linux.py
index dc7238a6..20dae7e6 100644
--- a/cibuildwheel/linux.py
+++ b/cibuildwheel/linux.py
@@ -145,6 +145,8 @@ def build(project_dir, output_dir, test_command, test_requires, test_extras, bef
                     venv_dir=`mktemp -d`/venv
                     python -m virtualenv "$venv_dir"
 
+                    export __CIBW_VIRTUALENV_PATH__=$venv_dir
+
                     # run the tests in a subshell to keep that `activate`
                     # script from polluting the env
                     (
diff --git a/cibuildwheel/macos.py b/cibuildwheel/macos.py
index dd2a412b..3b3edcba 100644
--- a/cibuildwheel/macos.py
+++ b/cibuildwheel/macos.py
@@ -209,6 +209,7 @@ def build(project_dir, output_dir, test_command, test_requires, test_extras, bef
                 os.path.join(venv_dir, 'bin'),
                 virtualenv_env['PATH'],
             ])
+            virtualenv_env["__CIBW_VIRTUALENV_PATH__"] = venv_dir
 
             # check that we are using the Python from the virtual environment
             call(['which', 'python'], env=virtualenv_env)
diff --git a/cibuildwheel/windows.py b/cibuildwheel/windows.py
index bd93e1db..f179be94 100644
--- a/cibuildwheel/windows.py
+++ b/cibuildwheel/windows.py
@@ -197,6 +197,7 @@ def build(project_dir, output_dir, test_command, test_requires, test_extras, bef
                 os.path.join(venv_dir, 'Scripts'),
                 virtualenv_env['PATH'],
             ])
+            virtualenv_env["__CIBW_VIRTUALENV_PATH__"] = venv_dir
 
             # check that we are using the Python from the virtual environment
             shell(['which', 'python'], env=virtualenv_env)
diff --git a/test/02_test/test/spam_test.py b/test/02_test/test/spam_test.py
index faf7e6bc..58ce05d0 100644
--- a/test/02_test/test/spam_test.py
+++ b/test/02_test/test/spam_test.py
@@ -1,9 +1,26 @@
+from __future__ import print_function
+import os
+import sys
 from unittest import TestCase
 
 import spam
 
 
+def normalize_path(path_str):
+    """because of windows short path"""
+    return os.path.normcase(path_str).replace("vssadm~1", "vssadministrator")
+
+
 class TestSpam(TestCase):
     def test_system(self):
         self.assertEqual(0, spam.system('python -c "exit(0)"'))
         self.assertNotEqual(0, spam.system('python -c "exit(1)"'))
+
+    def test_virtualenv(self):
+        virtualenv_path = normalize_path(os.environ.get("__CIBW_VIRTUALENV_PATH__"))
+        print("=[executable]", sys.executable)
+        print("=[spam location]", spam.__file__)
+        print("=[virtualenv path]", virtualenv_path)
+        self.assertTrue(virtualenv_path in normalize_path(sys.executable))
+        self.assertTrue(virtualenv_path in normalize_path(spam.__file__))
+