diff --git a/src/system/boot/platform/atari_m68k/fixup_tos_floppy_chksum.c b/src/system/boot/platform/atari_m68k/fixup_tos_floppy_chksum.c
index 8e410e6e22..ca44b403e1 100644
--- a/src/system/boot/platform/atari_m68k/fixup_tos_floppy_chksum.c
+++ b/src/system/boot/platform/atari_m68k/fixup_tos_floppy_chksum.c
@@ -1,27 +1,29 @@
 #include <stdio.h>
-#include <OS.h>
-#include <ByteOrder.h>
+#include <stdint.h>
+#include <fcntl.h>
 
-
-uint8 sector[512];
+uint8_t sector[512];
 
 int main(int argc, char **argv)
 {
 	int fd, i;
-	uint16 sum;
-	uint16 *p = (uint16 *)sector;
+	uint16_t sum;
+	uint8_t *p = sector;
 	fd = open(argv[1], O_RDWR);
 	if (fd < 0) {
 		return 1;
 	}
-	if (read(fd, sector, 512-2) < 512) {
+	if (read(fd, sector, 512-2) < 512-2) {
 		perror("read");
 		return 1;
 	}
-	for (sum = 0, i = 0; i < (512-2)/2; i++) {
-		sum += B_LENDIAN_TO_HOST_INT16(p[i]);
+	for (sum = 0, i = 0; i < (512-2); i++) {
+		sum += p[i];
 	}
-	p[(512-2)/2] = B_HOST_TO_BENDIAN_INT16(0x1234 - sum);
+	sum = 0x1234 - sum;
+	// big endian
+	p[512-2] = (uint8_t)(sum >> 8);
+	p[512-1] = (uint8_t)sum;
 	//lseek(fd, 0LL, SEEK_SET);
 	write(fd, &sector[512-2], 2);
 	return 0;
diff --git a/src/system/boot/platform/atari_m68k/shell.S b/src/system/boot/platform/atari_m68k/shell.S
index 2ae1fea74b..ab3ea363e1 100644
--- a/src/system/boot/platform/atari_m68k/shell.S
+++ b/src/system/boot/platform/atari_m68k/shell.S
@@ -75,7 +75,7 @@ floppy_start:
 	jsr			puts
 	bra			spin
 flopy_done:
-	jmp			#ATARI_ZBEOS_BASE+512
+	bra			#ATARI_ZBEOS_BASE+512
 
 /**	Loads %d2 sectors from floppy disk, starting at head XXX %dh, sector %cx.
  *	The data is loaded to %a2.