diff --git a/src/arch/x86/Makefile.inc b/src/arch/x86/Makefile.inc
index 07378920d8..a7d91a4753 100644
--- a/src/arch/x86/Makefile.inc
+++ b/src/arch/x86/Makefile.inc
@@ -91,6 +91,7 @@ else
 $(eval $(call early_x86_stage,bootblock,elf64-x86-64))
 endif
 
+$(call src-to-obj,bootblock,$(dir)/walkcbfs.S): $(obj)/fmap_config.h
 bootblock-y += walkcbfs.S
 
 endif # CONFIG_ARCH_BOOTBLOCK_X86_32 / CONFIG_ARCH_BOOTBLOCK_X86_64
diff --git a/src/arch/x86/walkcbfs.S b/src/arch/x86/walkcbfs.S
index 393bcf54ed..4608e2c12a 100644
--- a/src/arch/x86/walkcbfs.S
+++ b/src/arch/x86/walkcbfs.S
@@ -1,13 +1,6 @@
 /* SPDX-License-Identifier: GPL-2.0-only */
 
-#define CBFS_HEADER_PTR 0xfffffffc
-
-#define CBFS_HEADER_MAGIC 0
-#define CBFS_HEADER_VERSION (CBFS_HEADER_MAGIC + 4)
-#define CBFS_HEADER_ROMSIZE (CBFS_HEADER_VERSION + 4)
-#define CBFS_HEADER_BOOTBLOCKSIZE (CBFS_HEADER_ROMSIZE + 4)
-#define CBFS_HEADER_ALIGN (CBFS_HEADER_BOOTBLOCKSIZE + 4)
-#define CBFS_HEADER_OFFSET (CBFS_HEADER_ALIGN + 4)
+#include <fmap_config.h>
 
 /* we use this instead of CBFS_HEADER_ALIGN because the latter is retired. */
 #define CBFS_ALIGNMENT 64
@@ -33,14 +26,7 @@
 walkcbfs_asm:
 	cld
 
-	mov CBFS_HEADER_PTR, %eax
-	mov CBFS_HEADER_ROMSIZE(%eax), %ecx
-	bswap %ecx
-	mov $0, %ebx
-	sub %ecx, %ebx	/* ROM base address in ebx */
-	mov CBFS_HEADER_OFFSET(%eax), %ecx
-	bswap %ecx
-	add %ecx, %ebx	/* address where we start looking for LARCHIVEs */
+	movl $FMAP_SECTION_COREBOOT_START, %ebx
 
 	/* determine filename length */
 	mov $0, %eax
@@ -96,17 +82,11 @@ tryharder:
 	mov %ecx, %ebx
 
 check_for_exit:
-	/* look if we should exit: did we pass into the bootblock already? */
-	mov CBFS_HEADER_PTR, %ecx
-	mov CBFS_HEADER_BOOTBLOCKSIZE(%ecx), %ecx
-	bswap %ecx
-	not %ecx
-	add $1, %ecx
+	/* if addr <= COREBOOT_END - 1, continue */
+#define FMAP_SECTION_COREBOOT_END (FMAP_SECTION_COREBOOT_START - 1 + FMAP_SECTION_COREBOOT_SIZE)
 
+	movl $FMAP_SECTION_COREBOOT_END, %ecx
 	cmp %ecx, %ebx
-	/* if bootblockstart >= addr (==we're still in the data area),
-	 * jump back
-	 */
 	jbe walker
 
 out: