diff --git a/synapse/logging/utils.py b/synapse/logging/utils.py
index fea774e2e5..9d993324ba 100644
--- a/synapse/logging/utils.py
+++ b/synapse/logging/utils.py
@@ -22,6 +22,7 @@ _TIME_FUNC_ID = 0
 
 
 def _log_debug_as_f(f, msg, msg_args):
+    return
     name = f.__module__
     logger = logging.getLogger(name)