diff --git a/include/hydrolink/protocol.h b/include/hydrolink/protocol.h
index 37b425f..1bbda38 100644
--- a/include/hydrolink/protocol.h
+++ b/include/hydrolink/protocol.h
@@ -145,6 +145,16 @@ static inline uint16_t crc_xmodem_calculate(const uint8_t *data, uint8_t length)
   return crc;
 }
 
+static inline uint16_t hydrolink_calculate_crc(const uint8_t *payload, uint8_t length, uint8_t crc_extra) {
+  uint16_t crc;
+  crc_xmodem_init(&crc);
+  for(int i = 0; i < length; ++i) {
+    crc_xmodem_accumulate(payload[i], &crc);
+  }
+  crc_xmodem_accumulate(crc_extra, &crc);
+  return crc;
+}
+
 void hydrolink_fill_header_and_crc(hydrolink_msg_t *msg, uint8_t msg_id, uint8_t payload_length, uint8_t dst_id, uint8_t src_id, uint8_t crc_extra) {
   msg->id = msg_id;
   msg->payload_length = payload_length;