diff --git a/protob/messages.proto b/protob/messages.proto
index 244aab2fee..18f5fc5ab5 100644
--- a/protob/messages.proto
+++ b/protob/messages.proto
@@ -129,8 +129,8 @@ message Failure {
 // Computer should respond with ButtonAck message or Cancel to cancel
 // the original request.
 message ButtonRequest {
-	optional string code = 1;
-	optional string data = 2;
+	optional ButtonRequestType code = 1;
+	optional bytes data = 2 [(binary) = true];
 }
 
 // Computer agrees to wait for HW button press.
diff --git a/protob/types.proto b/protob/types.proto
index 8afb4b4c77..251d6597cc 100644
--- a/protob/types.proto
+++ b/protob/types.proto
@@ -48,6 +48,10 @@ enum RequestType {
 	TXOUTPUT = 1;
 }
 
+enum ButtonRequestType {
+	ButtonRequest_FeeOverThreshold = 1;
+}
+
 // Structure of BIP32 (hierarchical deterministic) node
 // Used for imports of private key into the device and exporting public key out of device
 message HDNodeType {