diff --git a/requirements.txt b/requirements.txt
index d730da3f47..4e2f85040f 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -10,7 +10,7 @@ debtcollector>=1.2.0 # Apache-2.0
 jsonpath-rw-ext>=0.1.9 # Apache-2.0
 lxml>=2.3 # BSD
 monotonic
-msgpack>=0.4.0 # Apache-2.0
+msgpack>=0.4.0,<1.0.0  # Apache-2.0
 oslo.concurrency>=3.5.0 # Apache-2.0
 oslo.config>=3.22.0 # Apache-2.0
 oslo.i18n>=2.1.0 # Apache-2.0