diff --git a/docs/sample_config.yaml b/docs/sample_config.yaml
index 6da1167632..43969bbb70 100644
--- a/docs/sample_config.yaml
+++ b/docs/sample_config.yaml
@@ -485,7 +485,8 @@ database:
 
 ## Logging ##
 
-# A yaml python logging config file
+# A yaml python logging config file as described by
+# https://docs.python.org/3.7/library/logging.config.html#configuration-dictionary-schema
 #
 log_config: "CONFDIR/SERVERNAME.log.config"
 
diff --git a/synapse/config/logger.py b/synapse/config/logger.py
index 981df5a10c..2704c18720 100644
--- a/synapse/config/logger.py
+++ b/synapse/config/logger.py
@@ -89,7 +89,8 @@ class LoggingConfig(Config):
             """\
         ## Logging ##
 
-        # A yaml python logging config file
+        # A yaml python logging config file as described by
+        # https://docs.python.org/3.7/library/logging.config.html#configuration-dictionary-schema
         #
         log_config: "%(log_config)s"
         """