diff --git a/setup.cfg b/setup.cfg
index 0536af6..4834fc8 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -21,6 +21,8 @@ classifiers =
     Programming Language :: Python
     Programming Language :: Python :: 2
     Programming Language :: Python :: 3
+    Programming Language :: Python :: Implementation :: CPython
+    Programming Language :: Python :: Implementation :: PyPy
     Topic :: Internet :: WWW/HTTP :: Dynamic Content
     Topic :: Software Development :: Libraries :: Python Modules
     Topic :: Text Processing :: Markup :: HTML