diff --git a/libraries/AP_Math/crc.cpp b/libraries/AP_Math/crc.cpp
index 767b762ab2..8d51f8d16f 100644
--- a/libraries/AP_Math/crc.cpp
+++ b/libraries/AP_Math/crc.cpp
@@ -49,11 +49,10 @@ static const uint8_t crc8_table[] = {
  */
 uint8_t crc_crc8(const uint8_t *p, uint8_t len)
 {
-	uint16_t i;
 	uint16_t crc = 0x0;
 
 	while (len--) {
-		i = (crc ^ *p++) & 0xFF;
+		const uint16_t i = (crc ^ *p++) & 0xFF;
 		crc = (crc8_table[i] ^ (crc << 8)) & 0xFF;
 	}