diff --git a/requirements.txt b/requirements.txt
index af01315..bdac3a4 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -2,12 +2,12 @@
 # of appearance. Changing the order has an impact on the overall integration
 # process, which may cause wedges in the gate later.
 
-pbr~=1.8
+pbr>=1.8,<1.9
 
-oslo.config~=2.4
-oslo.messaging~=2.5
-oslo.serialization~=1.9
-oslo.versionedobjects~=0.10
+oslo.config>=2.4,<2.5
+oslo.messaging>=2.5,<2.6
+oslo.serialization>=1.9,<1.10
+oslo.versionedobjects>=0.10,<0.11
 requests>=2.0.0,<3.0.0  # availability: 2.10.0 on CentOS 7, 2.7.0 on Ubuntu 14.04
-sqlalchemy~=1.0
-synergy-service~=1.0.1
+sqlalchemy>=1.0,<1.1
+synergy-service>=1.1,<1.2