diff --git a/plat/st/common/include/stm32mp_common.h b/plat/st/common/include/stm32mp_common.h
index e334f22..66b9310 100644
--- a/plat/st/common/include/stm32mp_common.h
+++ b/plat/st/common/include/stm32mp_common.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2018-2023, STMicroelectronics - All Rights Reserved
+ * Copyright (C) 2018-2024, STMicroelectronics - All Rights Reserved
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -14,6 +14,9 @@
 #define JEDEC_ST_BKID U(0x0)
 #define JEDEC_ST_MFID U(0x20)
 
+#define STM32MP_CHIP_SEC_CLOSED		U(0x34D9CCC5)
+#define STM32MP_CHIP_SEC_OPEN		U(0xA764D182)
+
 /* FWU configuration (max supported value is 15) */
 #define FWU_MAX_TRIAL_REBOOT		U(3)
 
@@ -23,8 +26,8 @@
 uint16_t stm32mp_get_boot_itf_selected(void);
 
 bool stm32mp_is_single_core(void);
-bool stm32mp_is_closed_device(void);
 bool stm32mp_is_auth_supported(void);
+uint32_t stm32mp_check_closed_device(void);
 
 /* Return the base address of the DDR controller */
 uintptr_t stm32mp_ddrctrl_base(void);
diff --git a/plat/st/common/stm32mp_crypto_lib.c b/plat/st/common/stm32mp_crypto_lib.c
index e282115..837c3d6 100644
--- a/plat/st/common/stm32mp_crypto_lib.c
+++ b/plat/st/common/stm32mp_crypto_lib.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2022-2023, STMicroelectronics - All Rights Reserved
+ * Copyright (c) 2022-2024, STMicroelectronics - All Rights Reserved
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -58,7 +58,8 @@
 		panic();
 	}
 
-	if (stm32mp_is_closed_device() || stm32mp_is_auth_supported()) {
+	if ((stm32mp_check_closed_device() == STM32MP_CHIP_SEC_CLOSED) ||
+	    stm32mp_is_auth_supported()) {
 #if STM32MP_CRYPTO_ROM_LIB
 		boot_context = (boot_api_context_t *)stm32mp_get_boot_ctx_address();
 		auth_ops.verify_signature = boot_context->bootrom_ecdsa_verify_signature;
@@ -322,7 +323,8 @@
 	size_t bignum_len = sizeof(sig) / 2U;
 	unsigned int seq_num = 0U;
 
-	if (!stm32mp_is_closed_device() && !stm32mp_is_auth_supported()) {
+	if ((stm32mp_check_closed_device() == STM32MP_CHIP_SEC_OPEN) &&
+	    !stm32mp_is_auth_supported()) {
 		return CRYPTO_SUCCESS;
 	}
 
diff --git a/plat/st/common/stm32mp_trusted_boot.c b/plat/st/common/stm32mp_trusted_boot.c
index 6d89290..d40fc55 100644
--- a/plat/st/common/stm32mp_trusted_boot.c
+++ b/plat/st/common/stm32mp_trusted_boot.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2022, STMicroelectronics - All Rights Reserved
+ * Copyright (c) 2022-2024, STMicroelectronics - All Rights Reserved
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -67,14 +67,14 @@
 		 * Check if key hash values in OTP are 0 or 0xFFFFFFFFF
 		 * programmed : Invalid Key
 		 */
-		if (!stm32mp_is_closed_device() && !valid) {
+		if ((stm32mp_check_closed_device() == STM32MP_CHIP_SEC_OPEN) && !valid) {
 			if ((tmp != 0U) && (tmp != 0xFFFFFFFFU) && (tmp != first)) {
 				valid = true;
 			}
 		}
 	}
 
-	if (!stm32mp_is_closed_device() && !valid) {
+	if ((stm32mp_check_closed_device() == STM32MP_CHIP_SEC_OPEN) && !valid) {
 		return 0;
 	}
 
@@ -163,7 +163,7 @@
 	*key_ptr = &root_pk_hash;
 	*flags = ROTPK_IS_HASH;
 
-	if ((res == 0) && !stm32mp_is_closed_device()) {
+	if ((res == 0) && (stm32mp_check_closed_device() == STM32MP_CHIP_SEC_OPEN)) {
 		*flags |= ROTPK_NOT_DEPLOYED;
 	}
 
diff --git a/plat/st/stm32mp1/bl2_plat_setup.c b/plat/st/stm32mp1/bl2_plat_setup.c
index eeabd09..321b8c5 100644
--- a/plat/st/stm32mp1/bl2_plat_setup.c
+++ b/plat/st/stm32mp1/bl2_plat_setup.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015-2023, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2015-2024, Arm Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -318,7 +318,7 @@
 
 skip_console_init:
 #if !TRUSTED_BOARD_BOOT
-	if (stm32mp_is_closed_device()) {
+	if (stm32mp_check_closed_device() == STM32MP_CHIP_SEC_CLOSED) {
 		/* Closed chip mandates authentication */
 		ERROR("Secure chip: TRUSTED_BOARD_BOOT must be enabled\n");
 		panic();
@@ -347,7 +347,7 @@
 	stm32_iwdg_refresh();
 
 	if (bsec_read_debug_conf() != 0U) {
-		if (stm32mp_is_closed_device()) {
+		if (stm32mp_check_closed_device() == STM32MP_CHIP_SEC_CLOSED) {
 #if DEBUG
 			WARN("\n%s", debug_msg);
 #else
diff --git a/plat/st/stm32mp1/stm32mp1_private.c b/plat/st/stm32mp1/stm32mp1_private.c
index ea35055..0e69513 100644
--- a/plat/st/stm32mp1/stm32mp1_private.c
+++ b/plat/st/stm32mp1/stm32mp1_private.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015-2023, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2015-2024, Arm Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -531,12 +531,12 @@
 }
 
 /* Return true when device is in closed state */
-bool stm32mp_is_closed_device(void)
+uint32_t stm32mp_check_closed_device(void)
 {
 	uint32_t value;
 
 	if (stm32_get_otp_value(CFG0_OTP, &value) != 0) {
-		return true;
+		return STM32MP_CHIP_SEC_CLOSED;
 	}
 
 #if STM32MP13
@@ -544,17 +544,22 @@
 
 	switch (value) {
 	case CFG0_OPEN_DEVICE:
-		return false;
+		return STM32MP_CHIP_SEC_OPEN;
 	case CFG0_CLOSED_DEVICE:
 	case CFG0_CLOSED_DEVICE_NO_BOUNDARY_SCAN:
 	case CFG0_CLOSED_DEVICE_NO_JTAG:
-		return true;
+		return STM32MP_CHIP_SEC_CLOSED;
 	default:
 		panic();
 	}
 #endif
 #if STM32MP15
-	return (value & CFG0_CLOSED_DEVICE) == CFG0_CLOSED_DEVICE;
+	if ((value & CFG0_CLOSED_DEVICE) == CFG0_CLOSED_DEVICE) {
+		return STM32MP_CHIP_SEC_CLOSED;
+	} else {
+		return STM32MP_CHIP_SEC_OPEN;
+	}
+
 #endif
 }