diff --git a/uncanny/message.go b/uncanny/message.go
index 7cd4dcb..0c2ecdd 100644
--- a/uncanny/message.go
+++ b/uncanny/message.go
@@ -355,7 +355,7 @@ func (f DisplayCommand) Encode() can.Frame {
 	copy(data[1:], f.Data[:length])
 	return can.Frame{
 		ID: uint32(C.can_msg_display_cmd),
-		Length: length + 1,
+		Length: uint8(length + 1),
 		Data: data,
 	}
 }