diff --git a/ssl/ssl_session.cc b/ssl/ssl_session.cc
index 77d3f4c..6635703 100644
--- a/ssl/ssl_session.cc
+++ b/ssl/ssl_session.cc
@@ -624,10 +624,14 @@
          ssl->server == session->is_server &&
          // The session must not be expired.
          ssl_session_is_time_valid(ssl, session) &&
-         /* Only resume if the session's version matches the negotiated
-          * version. */
+         // Only resume if the session's version matches the negotiated
+         // version.
          ssl->version == session->ssl_version &&
-         // Only resume if the session's cipher matches the negotiated one.
+         // Only resume if the session's cipher matches the negotiated one. This
+         // is stricter than necessary for TLS 1.3, which allows cross-cipher
+         // resumption if the PRF hashes match. We require an exact match for
+         // simplicity. If loosening this, the 0-RTT accept logic must be
+         // updated to check the cipher.
          hs->new_cipher == session->cipher &&
          // If the session contains a client certificate (either the full
          // certificate or just the hash) then require that the form of the