diff --git a/requirements.txt b/requirements.txt
index 1dababa85d..620a00c7fb 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -3,7 +3,7 @@
 # process, which may cause wedges in the gate later.
 pbr!=2.1.0,>=2.0.0 # Apache-2.0
 docker>=2.0.0 # Apache-2.0
-cryptography>=1.6 # BSD/Apache-2.0
+cryptography!=2.0,>=1.6 # BSD/Apache-2.0
 Jinja2!=2.9.0,!=2.9.1,!=2.9.2,!=2.9.3,!=2.9.4,>=2.8 # BSD License (3 clause)
 gitdb>=0.6.4 # BSD License (3 clause)
 GitPython>=1.0.1 # BSD License (3 clause)