1 files changed, 1 insertions, 1 deletions
diff --git a/synapse/logging/opentracing.py b/synapse/logging/opentracing.py
index 10bd4a1461..c6e6335740 100644
--- a/synapse/logging/opentracing.py
+++ b/synapse/logging/opentracing.py
@@ -262,7 +262,7 @@ logger = logging.getLogger(__name__)
 # Block everything by default
 # A regex which matches the server_names to expose traces for.
 # None means 'block everything'.
-_homeserver_whitelist = None
+_homeserver_whitelist = None  # type: Optional[re.Pattern[str]]
 
 # Util methods