diff --git a/src/tools/fixup_tos_boot_checksum/fixup_tos_boot_checksum.c b/src/tools/fixup_tos_boot_checksum/fixup_tos_boot_checksum.c
index 87fe8c9932..674ca40bc3 100644
--- a/src/tools/fixup_tos_boot_checksum/fixup_tos_boot_checksum.c
+++ b/src/tools/fixup_tos_boot_checksum/fixup_tos_boot_checksum.c
@@ -1,6 +1,7 @@
+#include <fcntl.h>
 #include <stdio.h>
 #include <stdint.h>
-#include <fcntl.h>
+#include <unistd.h>
 
 uint8_t sector[512];