diff --git a/setup.py b/setup.py
index 8e31d43..3526823 100644
--- a/setup.py
+++ b/setup.py
@@ -74,7 +74,7 @@ def get_sources(path, ignore_files):
     define_macros=[
             ("WITH_GREENLET",None),
             ("HTTP_PARSER_DEBUG", "0") ]
-    install_requires=['greenlet>=0.4.5,<0.5']
+    install_requires=['greenlet>=0.4.5,<2.0.0']
 
 if develop:
     define_macros.append(("DEVELOP",None))