diff --git a/extra-requirements.txt b/extra-requirements.txt
index a94eac336..faa63a7ea 100644
--- a/extra-requirements.txt
+++ b/extra-requirements.txt
@@ -3,4 +3,4 @@
 ansible>=2.4.0       # GPLv3
 os-faults>=0.1.18    # Apache-2.0
 tempest>=17.1.0      # Apache-2.0
-cryptography<=2.2.2
+cryptography<=2.2.2  # Apache-2.0