diff --git a/setup.py b/setup.py
index 2619bd544..06a36e2ba 100644
--- a/setup.py
+++ b/setup.py
@@ -56,6 +56,8 @@ setup(
         'Programming Language :: Python :: 3.4',
         'Programming Language :: Python :: 3.5',
         'Programming Language :: Python :: 3.6',
+        'Programming Language :: Python :: Implementation :: CPython',
+        'Programming Language :: Python :: Implementation :: PyPy',
         'Topic :: Internet :: WWW/HTTP',
         'Topic :: Software Development :: Libraries :: Application Frameworks',
         'Topic :: Software Development :: Libraries :: Python Modules',