diff --git a/ssdv.c b/ssdv.c
index 1f94e2a..9aefdc7 100644
--- a/ssdv.c
+++ b/ssdv.c
@@ -18,7 +18,6 @@
 
 #include <stdint.h>
 #include <string.h>
-#include <util/crc16.h>
 #include <avr/pgmspace.h>
 #include "ssdv.h"
 #include "rs8.h"
@@ -124,6 +123,25 @@ static void *dtblcpy(ssdv_t *s, const void *src, size_t n)
 	return(r);
 }
 
+static uint32_t crc32(void *data, size_t length)
+{
+	uint32_t crc, x;
+	uint8_t i, *d;
+	
+	for(d = data, crc = 0xFFFFFFFF; length; length--)
+	{
+		x = (crc ^ *(d++)) & 0xFF;
+		for(i = 8; i > 0; i--)
+		{
+			if(x & 1) x = (x >> 1) ^ 0xEDB88320;
+			else x >>= 1;
+		}
+		crc = (crc >> 8) ^ x;
+	}
+	
+	return(crc ^ 0xFFFFFFFF);
+}
+
 static uint32_t encode_callsign(char *callsign)
 {
 	uint32_t x;
@@ -754,9 +772,9 @@ char ssdv_enc_get_packet(ssdv_t *s)
 			
 			if(r == SSDV_BUFFER_FULL || r == SSDV_EOI)
 			{
-				uint16_t mcu_id     = s->packet_mcu_id;
-				uint8_t  mcu_offset = s->packet_mcu_offset;
-				uint16_t i, x;
+				uint16_t mcu_id       = s->packet_mcu_id;
+				uint8_t i, mcu_offset = s->packet_mcu_offset;
+				uint32_t x;
 				
 				if(mcu_offset != 0xFF && mcu_offset >= SSDV_PKT_SIZE_PAYLOAD)
 				{
@@ -793,10 +811,12 @@ char ssdv_enc_get_packet(ssdv_t *s)
 				if(s->out_len > 0) ssdv_memset_prng(s->outp, s->out_len);
 				
 				/* Calculate the CRC codes */
-				for(i = 1, x = 0xFFFF; i < SSDV_PKT_SIZE - SSDV_PKT_SIZE_RSCODES - SSDV_PKT_SIZE_CRC; i++)
-					x = _crc_xmodem_update(x, s->out[i]);
+				x = crc32(&s->out[1], SSDV_PKT_SIZE_CRCDATA);
 				
-				s->out[i++] = x >> 8;
+				i = 1 + SSDV_PKT_SIZE_CRCDATA;
+				s->out[i++] = (x >> 24) & 0xFF;
+				s->out[i++] = (x >> 16) & 0xFF;
+				s->out[i++] = (x >> 8) & 0xFF;
 				s->out[i++] = x & 0xFF;
 				
 				/* Generate the RS codes */
diff --git a/ssdv.h b/ssdv.h
index e85d8cd..06c4dc0 100644
--- a/ssdv.h
+++ b/ssdv.h
@@ -31,9 +31,10 @@
 /* Packet details */
 #define SSDV_PKT_SIZE         (0x100)
 #define SSDV_PKT_SIZE_HEADER  (0x0F)
-#define SSDV_PKT_SIZE_CRC     (0x02)
+#define SSDV_PKT_SIZE_CRC     (0x04)
 #define SSDV_PKT_SIZE_RSCODES (0x20)
 #define SSDV_PKT_SIZE_PAYLOAD (SSDV_PKT_SIZE - SSDV_PKT_SIZE_HEADER - SSDV_PKT_SIZE_CRC - SSDV_PKT_SIZE_RSCODES)
+#define SSDV_PKT_SIZE_CRCDATA (SSDV_PKT_SIZE_HEADER + SSDV_PKT_SIZE_PAYLOAD - 1)
 
 #define TBL_LEN (546) /* Maximum size of the DQT and DHT tables */
 #define HBUFF_LEN (16) /* Extra space for reading marker data */