diff --git a/setup.py b/setup.py
index c51a718e2..feb33f8f4 100644
--- a/setup.py
+++ b/setup.py
@@ -56,6 +56,7 @@ extras_require = {
         'pytest-cov',
         'pytest-mock',
         'typing-extensions>=4.3,<5',
+        'tzdata; sys_platform == "win32"',
     ],
 }