diff --git a/protob/messages.proto b/protob/messages.proto
index 2e107e033..981a5a11f 100644
--- a/protob/messages.proto
+++ b/protob/messages.proto
@@ -622,6 +622,7 @@ message EthereumSignTx {
 	optional bytes value = 6;			// <=256 bit unsigned big endian (in wei)
 	optional bytes data_initial_chunk = 7;		// The initial data chunk (<= 1024 bytes)
 	optional uint32 data_length = 8;		// Length of transaction payload
+	optional uint32 chain_id = 9;			// Chain Id for EIP 155
 }
 
 /**