diff --git a/src/soc/amd/phoenix/Makefile.inc b/src/soc/amd/phoenix/Makefile.inc
index 0e42b98..566db26 100644
--- a/src/soc/amd/phoenix/Makefile.inc
+++ b/src/soc/amd/phoenix/Makefile.inc
@@ -131,13 +131,17 @@
 # type = 0x63 - construct APOB NV base/size from flash map
 # The flashmap section used for this is expected to be named RW_MRC_CACHE
 APOB_NV_SIZE=$(call get_fmap_value,FMAP_SECTION_RW_MRC_CACHE_SIZE)
-APOB_NV_BASE=$(call get_fmap_value,FMAP_SECTION_RW_MRC_CACHE_START)
+APOB_NV_BASE=$(shell printf "%#x" $(call int-subtract, \
+	$(call get_fmap_value,FMAP_SECTION_RW_MRC_CACHE_START) \
+	$(call get_fmap_value,FMAP_SECTION_FLASH_START)))
 
 ifeq ($(CONFIG_HAS_RECOVERY_MRC_CACHE),y)
 # On boards with recovery MRC cache, point type 0x63 entry to RECOVERY_MRC_CACHE.
 # Else use RW_MRC_CACHE. This entry will be added in the RO section.
 APOB_NV_RO_SIZE=$(call get_fmap_value,FMAP_SECTION_RECOVERY_MRC_CACHE_SIZE)
-APOB_NV_RO_BASE=$(call get_fmap_value,FMAP_SECTION_RECOVERY_MRC_CACHE_START)
+APOB_NV_RO_BASE=$(shell printf "%#x" $(call int-subtract, \
+	$(call get_fmap_value,FMAP_SECTION_RECOVERY_MRC_CACHE_START) \
+	$(call get_fmap_value,FMAP_SECTION_FLASH_START)))
 else
 APOB_NV_RO_SIZE=$(APOB_NV_SIZE)
 APOB_NV_RO_BASE=$(APOB_NV_BASE)