diff --git a/setup.py b/setup.py
index f5b7470..44f6a56 100755
--- a/setup.py
+++ b/setup.py
@@ -43,6 +43,7 @@ See http://propka.org/ for the PROPKA web server.
         'License :: OSI Approved :: GNU Lesser General Public License v2 (LGPLv2)',
         'Operating System :: POSIX', 
         'Operating System :: MacOS :: MacOS X',
+        'Operating System :: Microsoft :: Windows',
         'Programming Language :: Python',
         'Programming Language :: Python :: 3.5',
         'Programming Language :: Python :: 3.6',