diff --git a/aiofiles/__init__.py b/aiofiles/__init__.py
index dbb51cf..2028126 100644
--- a/aiofiles/__init__.py
+++ b/aiofiles/__init__.py
@@ -3,4 +3,4 @@
 
 __version__ = "0.5.0.dev0"
 
-__all__ = (open,)
+__all__ = ['open']