diff --git a/plat/st/stm32mp1/stm32mp1_private.c b/plat/st/stm32mp1/stm32mp1_private.c
index 6e729b5..f1f7e37 100644
--- a/plat/st/stm32mp1/stm32mp1_private.c
+++ b/plat/st/stm32mp1/stm32mp1_private.c
@@ -37,7 +37,12 @@
 					 BOARD_ID_VARFG_SHIFT)
 #define BOARD_ID2BOM(_id)		((_id) & BOARD_ID_BOM_MASK)
 
+#if STM32MP13
+#define TAMP_BOOT_MODE_BACKUP_REG_ID	U(30)
+#endif
+#if STM32MP15
 #define TAMP_BOOT_MODE_BACKUP_REG_ID	U(20)
+#endif
 #define TAMP_BOOT_MODE_ITF_MASK		U(0x0000FF00)
 #define TAMP_BOOT_MODE_ITF_SHIFT	8