diff --git a/PROTOCOL.sshsig b/PROTOCOL.sshsig
index 720e1f18a..db18458fa 100644
--- a/PROTOCOL.sshsig
+++ b/PROTOCOL.sshsig
@@ -71,7 +71,7 @@ encoding rules for the chosen key type. For RSA signatures, the
 signature algorithm must be "rsa-sha2-512" or "rsa-sha2-256" (i.e.
 not the legacy RSA-SHA1 "ssh-rsa").
 
-This blob is encoded as a string using the RFC4243 encoding
+This blob is encoded as a string using the RFC4253 encoding
 rules and base64 encoded to form the middle part of the
 armored signature.