diff --git a/eth/p2p/rlpx.nim b/eth/p2p/rlpx.nim
index 7a4cefa..7afb215 100644
--- a/eth/p2p/rlpx.nim
+++ b/eth/p2p/rlpx.nim
@@ -1000,7 +1000,8 @@ proc p2pProtocolBackendImpl*(protocol: P2PProtocol): Backend =
       var `rlpWriter` = `initRlpWriter`()
       const `perProtocolMsgIdVar` {.used.} = `msgId`
       let `perPeerMsgIdVar` = `perPeerMsgIdValue`
-      `append`(`rlpWriter`, `perPeerMsgIdVar`.uint)
+      # TODO: rlpx should error if perPeerMsgIdVar is signed
+      `append`(`rlpWriter`, `perPeerMsgIdVar`)
 
     when tracingEnabled:
       appendParams.add logSentMsgFields(peerVar, protocol, msgId, paramsToWrite)