diff --git a/setup.cfg b/setup.cfg
index 19382ddd..2bdcccd8 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -29,7 +29,7 @@ setup_requires =
         setuptools_scm >= 3.4
 install_requires =
         epsilon >= 0.7.0
-        twisted >= 13.2.0
+        twisted[tls] >= 13.2.0
 scripts =
         bin/axiomatic
 include_package_data = True