diff --git a/setup.py b/setup.py
index 8bc484c9a..67b9c02cf 100644
--- a/setup.py
+++ b/setup.py
@@ -35,6 +35,7 @@ def run(cls):
     version=__version__,
 
     tests_require=test_require,
+    extras_require={"crc32c": ["crc32c"]},
     cmdclass={"test": Tox},
     packages=find_packages(exclude=['test']),
     author="Dana Powers",