diff --git a/src/soc/amd/common/block/apob/apob_cache.c b/src/soc/amd/common/block/apob/apob_cache.c
index d70adfc5b2..d9a7067683 100644
--- a/src/soc/amd/common/block/apob/apob_cache.c
+++ b/src/soc/amd/common/block/apob/apob_cache.c
@@ -17,6 +17,7 @@
 #include <thread.h>
 #include <timestamp.h>
 #include <types.h>
+#include <pc80/mc146818rtc.h>
 
 #define DEFAULT_MRC_CACHE	"RW_MRC_CACHE"
 #define DEFAULT_MRC_CACHE_SIZE	FMAP_SECTION_RW_MRC_CACHE_SIZE
@@ -272,6 +273,10 @@ static void soc_update_apob_cache(void *unused)
 	if (CONFIG(SOC_AMD_COMMON_BLOCK_APOB_HASH))
 		update_apob_nv_hash(ram_hash, &write_rdev);
 
+	// update the signature in CMOS to indicate APOB updated.
+	cmos_write(0x5A, 0x86);
+	cmos_write(0xA5, 0x87);
+
 	timestamp_add_now(TS_AMD_APOB_END);
 
 	printk(BIOS_INFO, "Updated APOB in flash\n");