diff --git a/requirements.txt b/requirements.txt
index d9368e0..8ba92bf 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -2,6 +2,6 @@
 # of appearance. Changing the order has an impact on the overall integration
 # process, which may cause wedges in the gate later.
 
-dnspython>=1.12.0,!=1.13.0;python_version<'3.0'  # http://www.dnspython.org/LICENSE
-dnspython3>=1.12.0;python_version>='3.0'  # http://www.dnspython.org/LICENSE
+dnspython!=1.13.0,>=1.12.0;python_version<'3.0' # http://www.dnspython.org/LICENSE
+dnspython3>=1.12.0;python_version>='3.0' # http://www.dnspython.org/LICENSE
 tempest>=11.0.0 # Apache-2.0