diff --git a/tests/tools.py b/tests/tools.py
index e62d429c0..cf2ce6d82 100644
--- a/tests/tools.py
+++ b/tests/tools.py
@@ -21,8 +21,9 @@ VER_3_4 = (3, 4)
 VER_3_5 = (3, 5)
 VER_MAJOR_MINOR = sys.version_info[:2]
 VER_FULL = sys.version_info[:3]
-ON_DARWIN = platform.ON_DARWIN
-ON_WINDOWS = platform.ON_WINDOWS
+ON_DARWIN = (platform.system() == 'Darwin')
+ON_WINDOWS = (platform.system() == 'Windows')
+
 
 def sp(cmd):
     return subprocess.check_output(cmd, universal_newlines=True)