diff --git a/requirements.txt b/requirements.txt
index eef988d0..a829cd1f 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,2 +1,2 @@
 gevent>=1.1.0
-msgpack-python>=0.4.4
+msgpack-python>=0.4.4,<0.5.5