diff --git a/setup.py b/setup.py
index 00a4a97..6222a7b 100644
--- a/setup.py
+++ b/setup.py
@@ -71,6 +71,7 @@ setup(
         'Topic :: Security :: Cryptography',
         'Programming Language :: Python',
         'Programming Language :: Python :: 2',
+        'Programming Language :: Python :: 2.5',
         'Programming Language :: Python :: 2.6',
         'Programming Language :: Python :: 2.7',
         'Programming Language :: Python :: 2 :: Only',