diff --git a/draft-ietf-quic-tls.md b/draft-ietf-quic-tls.md
index 43ed620134..a9c673b520 100644
--- a/draft-ietf-quic-tls.md
+++ b/draft-ietf-quic-tls.md
@@ -1452,6 +1452,9 @@ without needing to receive the first packet that triggered the change.  An
 endpoint that notices a changed Key Phase bit updates keys and decrypts the
 packet that contains the changed value.
 
+Initiating a key update results in both endpoints updating keys.  This differs
+from TLS where endpoints can update keys independently.
+
 This mechanism replaces the key update mechanism of TLS, which relies on
 KeyUpdate messages sent using 1-RTT encryption keys.  Endpoints MUST NOT send a
 TLS KeyUpdate message.  Endpoints MUST treat the receipt of a TLS KeyUpdate