diff --git a/requirements.txt b/requirements.txt
index a4e7df1..27704b5 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -7,7 +7,7 @@
 # adding a new feature to oslo.serialization means adding a new dependency,
 # that is a likely indicator that the feature belongs somewhere else.
 
-pbr<2.0,>=1.4
+pbr<2.0,>=1.6
 Babel>=1.3
 six>=1.9.0
 msgpack-python>=0.4.0