diff --git a/libraries/AP_Math/crc.h b/libraries/AP_Math/crc.h
index d8abbd5b97..1b657416c1 100644
--- a/libraries/AP_Math/crc.h
+++ b/libraries/AP_Math/crc.h
@@ -19,5 +19,5 @@
 
 uint8_t crc_crc8(const uint8_t *p, uint8_t len);
 uint16_t crc_xmodem_update(uint16_t crc, uint8_t data);
-uint16_t crc_xmodem(const uint8_t *b, uint16_t len);
+uint16_t crc_xmodem(const uint8_t *data, uint16_t len);
 uint32_t crc_crc32(uint32_t crc, const uint8_t *buf, uint32_t size);