diff --git a/setup.py b/setup.py
index 6ef292f..332ad45 100644
--- a/setup.py
+++ b/setup.py
@@ -17,7 +17,7 @@ trove_classifiers = [
 setup(name="magic-wormhole-mailbox-server",
       version=versioneer.get_version(),
       description="Securely transfer data between computers",
-      long_description=open('README.md', 'rU').read(),
+      long_description=open('README.md').read(),
       long_description_content_type='text/markdown',
       author="Brian Warner",
       author_email="warner-magic-wormhole@lothar.com",