diff --git a/README.md b/README.md
index 69d7bb4..32936c6 100644
--- a/README.md
+++ b/README.md
@@ -173,8 +173,9 @@ users (requirement for internal-sftp). E.g. make `brmdoor-web` (used for sftp up
 For SFTP upload to work, target host needs to already to be in `~/.ssh/known_hosts` when making connection, otherwise
 you'll get an exception. Simply connect via command-line sftp before running, check and accept the fingeprint beforehand.
 
-Also, as noted before, reader should be behind door. PIN to open door should be in no case accessible from outside the
-door (unbelievably I've seen some commercial systems designed like this).
+Also, as noted before, reader should be behind door (mostly for vandalism). But the reader is not connected directly to 
+*open* PIN, so it's not possible to simply apply voltage to it in this design even if you expose the reader.
+PIN to open door should be in no case accessible from outside the door (like having Raspi on the outside).
 
 ## Known bugs (TODO)