diff --git a/requirements.txt b/requirements.txt
index 574d774..54d11e2 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -4,7 +4,7 @@
 cliff>=1.14.0 # Apache-2.0
 jsonschema!=2.5.0,<3.0.0,>=2.0.0
 oslo.utils>=2.0.0 # Apache-2.0
-pbr<2.0,>=1.4
+pbr<2.0,>=1.6
 python-keystoneclient>=1.6.0
 requests>=2.5.2
 six>=1.9.0