--- a/setup.py	2019-07-22 20:18:46.000000000 +0200
+++ b/setup.py	2019-08-01 21:49:28.107607851 +0200
@@ -238,7 +238,7 @@
     install_requires=[
         'six>=1.11.0',       # MIT license
         'txaio>=18.8.1',     # MIT license
-        'cryptography>=2.7', # BSD *or* Apache license
+        'cryptography>=2.6.1', # BSD *or* Apache license
     ],
     extras_require={
         'all': extras_require_all,