diff --git a/Lib/distutils/tests/test_sysconfig.py b/Lib/distutils/tests/test_sysconfig.py
index 4bf6a067d4d926..8ad5b5bde95d2a 100644
--- a/Lib/distutils/tests/test_sysconfig.py
+++ b/Lib/distutils/tests/test_sysconfig.py
@@ -81,6 +81,7 @@ def test_customize_compiler(self):
         os.environ['CC'] = 'my_cc'
         os.environ['ARFLAGS'] = '--myarflags'
         os.environ['CFLAGS'] = '--mycflags'
+        os.environ.pop('CPPFLAGS', None)
 
         # make sure AR gets caught
         class compiler: