diff --git a/plat/st/common/include/stm32mp_common.h b/plat/st/common/include/stm32mp_common.h
index 9ca5d16..7508004 100644
--- a/plat/st/common/include/stm32mp_common.h
+++ b/plat/st/common/include/stm32mp_common.h
@@ -113,4 +113,8 @@
 void stm32_save_boot_interface(uint32_t interface, uint32_t instance);
 void stm32_get_boot_interface(uint32_t *interface, uint32_t *instance);
 
+#if !STM32MP_USE_STM32IMAGE && PSA_FWU_SUPPORT
+void stm32mp1_fwu_set_boot_idx(void);
+#endif /* !STM32MP_USE_STM32IMAGE && PSA_FWU_SUPPORT */
+
 #endif /* STM32MP_COMMON_H */
diff --git a/plat/st/stm32mp1/bl2_plat_setup.c b/plat/st/stm32mp1/bl2_plat_setup.c
index 0c93f27..b5fc3ff 100644
--- a/plat/st/stm32mp1/bl2_plat_setup.c
+++ b/plat/st/stm32mp1/bl2_plat_setup.c
@@ -30,6 +30,7 @@
 #include <plat/common/platform.h>
 
 #include <platform_def.h>
+#include <stm32mp_common.h>
 #include <stm32mp1_dbgmcu.h>
 
 static struct stm32mp_auth_ops stm32mp1_auth_ops;
@@ -452,6 +453,9 @@
 		bl32_mem_params = get_bl_mem_params_node(BL32_IMAGE_ID);
 		assert(bl32_mem_params != NULL);
 		bl32_mem_params->ep_info.lr_svc = bl_mem_params->ep_info.pc;
+#if !STM32MP_USE_STM32IMAGE && PSA_FWU_SUPPORT
+		stm32mp1_fwu_set_boot_idx();
+#endif /* !STM32MP_USE_STM32IMAGE && PSA_FWU_SUPPORT */
 		break;
 
 	default:
diff --git a/plat/st/stm32mp1/stm32mp1_private.c b/plat/st/stm32mp1/stm32mp1_private.c
index 0bed12a..9016b0d 100644
--- a/plat/st/stm32mp1/stm32mp1_private.c
+++ b/plat/st/stm32mp1/stm32mp1_private.c
@@ -13,6 +13,7 @@
 #include <lib/xlat_tables/xlat_tables_v2.h>
 #include <libfdt.h>
 
+#include <plat/common/platform.h>
 #include <platform_def.h>
 
 /* Internal layout of the 32bit OTP word board_id */
@@ -40,6 +41,8 @@
 #define TAMP_BOOT_MODE_ITF_MASK		U(0x0000FF00)
 #define TAMP_BOOT_MODE_ITF_SHIFT	8
 
+#define TAMP_BOOT_COUNTER_REG_ID	U(21)
+
 #if defined(IMAGE_BL2)
 #define MAP_SEC_SYSRAM	MAP_REGION_FLAT(STM32MP_SYSRAM_BASE, \
 					STM32MP_SYSRAM_SIZE, \
@@ -597,3 +600,13 @@
 	*interface = itf >> 4;
 	*instance = itf & 0xFU;
 }
+
+#if !STM32MP_USE_STM32IMAGE && PSA_FWU_SUPPORT
+void stm32mp1_fwu_set_boot_idx(void)
+{
+	clk_enable(RTCAPB);
+	mmio_write_32(tamp_bkpr(TAMP_BOOT_COUNTER_REG_ID),
+		      plat_fwu_get_boot_idx());
+	clk_disable(RTCAPB);
+}
+#endif /* !STM32MP_USE_STM32IMAGE && PSA_FWU_SUPPORT */