diff --git a/synapse/crypto/context_factory.py b/synapse/crypto/context_factory.py
index 6fda5e677d..6ebbd3b73c 100644
--- a/synapse/crypto/context_factory.py
+++ b/synapse/crypto/context_factory.py
@@ -145,7 +145,10 @@ class ClientTLSOptionsFactory(object):
         should_verify = self._config.federation_verify_certificates
 
         # Check if we've disabled certificate verification for this host
-        if should_verify and host in self._config.federation_certificate_verification_whitelist:
+        if (
+            should_verify and
+            host in self._config.federation_certificate_verification_whitelist
+        ):
             should_verify = False
 
         if should_verify: