diff --git a/src/image.c b/src/image.c
index 35c347d..66ebb58 100644
--- a/src/image.c
+++ b/src/image.c
@@ -15,9 +15,10 @@
 #include "image.h"
 #include "nmgr.h"
 #include "cbor.h"
+#include "sha256.h"
 
 #define IMAGE_CHUNK_SIZE 124
-#define MACRO_CHUNK_SIZE 340
+#define MACRO_CHUNK_SIZE 512
 
 #define CRC16_INITIAL_CRC       0       /* what to seed crc16 with */
 #define CRC_CITT_POLYMINAL 0x1021
@@ -172,27 +173,37 @@ static void do_version(void) {
 }
 
 static void wrap_and_send_pkt(uint8_t *data, size_t len) {
-    fprintf(stderr, "Trying to wrap %d bytes", len);
+    static uint8_t seq = 66;
     uint8_t b64_buf[BOOT_SERIAL_OUT_MAX*2];
-    struct nmgr_hdr hdr;
+    uint16_t tot_len = len + sizeof(struct nmgr_hdr) + 2; // 2 is crc
+    struct nmgr_hdr hdr = {0};
     hdr.nh_op = NMGR_OP_WRITE;
     hdr.nh_group = htons(MGMT_GROUP_ID_IMAGE);
     hdr.nh_id = IMGMGR_NMGR_ID_UPLOAD;
-    hdr.nh_seq = 66;
+    hdr.nh_seq = seq++;
+    hdr.nh_len = htons(573);
 
     uint16_t crc = crc16((uint8_t*)&hdr, sizeof(struct nmgr_hdr), CRC_CITT_POLYMINAL, CRC16_INITIAL_CRC, false);
     crc = crc16(data, len, CRC_CITT_POLYMINAL, crc, true);
     crc = htons(crc);
-
-    uint16_t tot_len = len + sizeof(struct nmgr_hdr) + sizeof(crc);
+    
     uint16_t net_len = htons(tot_len);
 
     uint8_t *pos = b64_buf;
-    memcpy(b64_buf, &net_len, sizeof(tot_len));
-    pos += sizeof(tot_len);
+    memcpy(pos, &net_len, sizeof(tot_len));
+    pos += sizeof(net_len);
+
+    memcpy(pos, &hdr, sizeof(struct nmgr_hdr));
+    pos += sizeof(struct nmgr_hdr);
     memcpy(pos, data, len);
     pos += len;
     memcpy(pos, &crc, sizeof(crc));
+    printlen(b64_buf + 2, tot_len);
+    fflush(stdout);
+
+    // Check CRC
+    uint16_t crc2 = crc16(b64_buf+2, tot_len, CRC_CITT_POLYMINAL, CRC16_INITIAL_CRC, true);
+    assert(!crc2);
 
     size_t out_len;
     uint8_t *out_buf = base64_encode(b64_buf, tot_len, &out_len);
@@ -233,10 +244,9 @@ void do_upload(char *filename){
         CborEncoder root, map;
         uint8_t cbor_buf[BOOT_SERIAL_OUT_MAX*2];
         cbor_encoder_init(&root, cbor_buf, BOOT_SERIAL_OUT_MAX*2, 0);
-        cbor_encoder_create_map(&root, &map, pos == 0 ? 3 : 2);
+        cbor_encoder_create_map(&root, &map, pos == 0 ? 4 : 3);
 
         cbor_encode_text_stringz(&map, "data");
-
         uint8_t data[MACRO_CHUNK_SIZE];
         int actual_size;
         if ((actual_size = read(fd, data, MACRO_CHUNK_SIZE)) < MACRO_CHUNK_SIZE) {
@@ -255,8 +265,16 @@ void do_upload(char *filename){
         cbor_encode_text_stringz(&map, "off");
         cbor_encode_uint(&map, pos);
 
+        cbor_encode_text_stringz(&map, "sha");
+        SHA256_CTX sha_ctx;
+        sha256_init(&sha_ctx);
+        sha256_update(&sha_ctx, data, actual_size);
+        uint8_t sha[32];
+        sha256_final(&sha_ctx, (BYTE *)&sha);
+        cbor_encode_byte_string(&map, sha, 32);
+
         cbor_encoder_close_container(&root, &map);
-        wrap_and_send_pkt(data, cbor_encoder_get_buffer_size(&root, cbor_buf));
+        wrap_and_send_pkt(cbor_buf, cbor_encoder_get_buffer_size(&root, cbor_buf));
 
         uint8_t resp_buf[BOOT_SERIAL_IN_MAX];
         size_t in_len;