diff --git a/protocol/packet.hpp b/protocol/packet.hpp
index 481ba23..bfe4a09 100644
--- a/protocol/packet.hpp
+++ b/protocol/packet.hpp
@@ -40,8 +40,8 @@ typedef enum {
 } zcan_cmd_packet_type_t;
 
 static inline bool zcr_cmd_checkpacket(const zcr_cmd_header_t* header, int len) {
-  if (len < sizeof(zcr_cmd_header_t)) return false;
-  if ((header->datalen + sizeof(zcr_cmd_header_t) + 1) != len) return false;
+  if (len < (int)sizeof(zcr_cmd_header_t)) return false;
+  if ((int)(header->datalen + sizeof(zcr_cmd_header_t) + 1) != len) return false;
 
   uint8_t checksum = 0;
   for (int i = 0; i < len - 1; i++) checksum += ((uint8_t*)header)[i];