diff --git a/synapse/config/repository.py b/synapse/config/repository.py
index 88100798485c..2c6f57168e07 100644
--- a/synapse/config/repository.py
+++ b/synapse/config/repository.py
@@ -167,6 +167,8 @@ def default_config(self, **kwargs):
         # - '10.0.0.0/8'
         # - '172.16.0.0/12'
         # - '192.168.0.0/16'
+        # - '100.64.0.0/10'
+        # - '169.254.0.0/16'
         #
         # List of IP address CIDR ranges that the URL preview spider is allowed
         # to access even if they are specified in url_preview_ip_range_blacklist.