diff --git a/matrix/m.room.power_levels/README.md b/matrix/m.room.power_levels/README.md
index 9873f4a..965a513 100644
--- a/matrix/m.room.power_levels/README.md
+++ b/matrix/m.room.power_levels/README.md
@@ -26,7 +26,10 @@ This has the rest event in two forms, but doesn't duplicate the above.
 
 Generic notes:
 
-* Don't have any state events specified as 0.
+* Don't have anything in `events {}` as `0` or otherwise users will be
+  able to send state events with that name including gigabytes of
+  data breaking the room.
+  * Refer to security considerations of MSC 3779.
 
 ### Reasonable version