diff --git a/lightning/src/ln/msgs.rs b/lightning/src/ln/msgs.rs
index 30f6bd4c974..c2925d7354d 100644
--- a/lightning/src/ln/msgs.rs
+++ b/lightning/src/ln/msgs.rs
@@ -1514,12 +1514,12 @@ impl_writeable!(ChannelAnnouncement, {
 
 impl Writeable for UnsignedChannelUpdate {
 	fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
-		// `must_be_one` used to be `message_flags` but was deprecated in the spec.
-		const MUST_BE_ONE: u8 = 1;
+		// `message_flags` used to indicate presence of `htlc_maximum_msat`, but was deprecated in the spec.
+		const MESSAGE_FLAGS: u8 = 1;
 		self.chain_hash.write(w)?;
 		self.short_channel_id.write(w)?;
 		self.timestamp.write(w)?;
-		let all_flags = self.flags as u16 | ((MUST_BE_ONE as u16) << 8);
+		let all_flags = self.flags as u16 | ((MESSAGE_FLAGS as u16) << 8);
 		all_flags.write(w)?;
 		self.cltv_expiry_delta.write(w)?;
 		self.htlc_minimum_msat.write(w)?;
@@ -1539,7 +1539,7 @@ impl Readable for UnsignedChannelUpdate {
 			timestamp: Readable::read(r)?,
 			flags: {
 				let flags: u16 = Readable::read(r)?;
-				// Note: we ignore `must_be_one`, formely `message_flags`, since it was deprecated by the spec.
+				// Note: we ignore the `message_flags` for now, since it was deprecated by the spec.
 				flags as u8
 			},
 			cltv_expiry_delta: Readable::read(r)?,