diff --git a/libraries/GCS_MAVLink/GCS_MAVLink.h b/libraries/GCS_MAVLink/GCS_MAVLink.h
index 03555c1b56..ffa6d37feb 100644
--- a/libraries/GCS_MAVLink/GCS_MAVLink.h
+++ b/libraries/GCS_MAVLink/GCS_MAVLink.h
@@ -125,6 +125,15 @@ static inline uint16_t comm_get_txspace(mavlink_channel_t chan)
     return (uint16_t)ret;
 }
 
+#ifdef HAVE_CRC_ACCUMULATE
+// use the AVR C library implementation. This is a bit over twice as
+// fast as the C version
+static inline void crc_accumulate(uint8_t data, uint16_t *crcAccum)
+{
+	*crcAccum = _crc_ccitt_update(*crcAccum, data);
+}
+#endif
+
 #define MAVLINK_USE_CONVENIENCE_FUNCTIONS
 #include "include/mavlink/v1.0/ardupilotmega/mavlink.h"
 
diff --git a/libraries/GCS_MAVLink/include/mavlink/v1.0/checksum.h b/libraries/GCS_MAVLink/include/mavlink/v1.0/checksum.h
index 4f4cce02fc..5363084f74 100644
--- a/libraries/GCS_MAVLink/include/mavlink/v1.0/checksum.h
+++ b/libraries/GCS_MAVLink/include/mavlink/v1.0/checksum.h
@@ -24,6 +24,7 @@ extern "C" {
  * @param data new char to hash
  * @param crcAccum the already accumulated checksum
  **/
+#ifndef HAVE_CRC_ACCUMULATE
 static inline void crc_accumulate(uint8_t data, uint16_t *crcAccum)
 {
         /*Accumulate one byte of data into the CRC*/
@@ -33,6 +34,7 @@ static inline void crc_accumulate(uint8_t data, uint16_t *crcAccum)
         tmp ^= (tmp<<4);
         *crcAccum = (*crcAccum>>8) ^ (tmp<<8) ^ (tmp <<3) ^ (tmp>>4);
 }
+#endif
 
 /**
  * @brief Initiliaze the buffer for the X.25 CRC