diff --git a/src/soc/amd/stoneyridge/cpu.c b/src/soc/amd/stoneyridge/cpu.c
index 94beed8..7f71703 100644
--- a/src/soc/amd/stoneyridge/cpu.c
+++ b/src/soc/amd/stoneyridge/cpu.c
@@ -1,5 +1,6 @@
 /* SPDX-License-Identifier: GPL-2.0-only */
 
+#include <amdblocks/iomap.h>
 #include <amdblocks/mca.h>
 #include <amdblocks/reset.h>
 #include <amdblocks/smm.h>
@@ -61,7 +62,8 @@
 				"mp_init_with_smm failed. Halting.\n");
 
 	/* The flash is now no longer cacheable. Reset to WP for performance. */
-	mtrr_use_temp_range(FLASH_BASE_ADDR, CONFIG_ROM_SIZE, MTRR_TYPE_WRPROT);
+	mtrr_use_temp_range(FLASH_BELOW_4GB_MAPPING_REGION_BASE,
+			    FLASH_BELOW_4GB_MAPPING_REGION_SIZE, MTRR_TYPE_WRPROT);
 
 	set_warm_reset_flag();
 }