diff --git a/hal/TARGET_FLASH_CMSIS_ALGO/flash_common_algo.c b/hal/TARGET_FLASH_CMSIS_ALGO/flash_common_algo.c
index 1404d4dd94..ebdad9e4f1 100644
--- a/hal/TARGET_FLASH_CMSIS_ALGO/flash_common_algo.c
+++ b/hal/TARGET_FLASH_CMSIS_ALGO/flash_common_algo.c
@@ -19,7 +19,7 @@
 #include "mbed_critical.h"
 #include "mbed_toolchain.h"
 
-#ifndef __DOMAIN_NS
+#ifndef DOMAIN_NS
 
 #if defined (__ARM_FEATURE_CMSE) && (__ARM_FEATURE_CMSE == 3U)
 #include <arm_cmse.h>
@@ -260,4 +260,4 @@ MBED_NONSECURE_ENTRY uint32_t flash_get_size(const flash_t *obj)
     return obj->target_config->flash_size;
 }
 
-#endif  // #ifndef __DOMAIN_NS
+#endif  // #ifndef DOMAIN_NS
diff --git a/tools/toolchains/__init__.py b/tools/toolchains/__init__.py
index c95b1c0068..ef4b3974f7 100644
--- a/tools/toolchains/__init__.py
+++ b/tools/toolchains/__init__.py
@@ -377,11 +377,11 @@ class mbedToolchain:
         "Cortex-M7F" : ["__CORTEX_M7", "ARM_MATH_CM7", "__FPU_PRESENT=1", "__CMSIS_RTOS", "__MBED_CMSIS_RTOS_CM"],
         "Cortex-M7FD" : ["__CORTEX_M7", "ARM_MATH_CM7", "__FPU_PRESENT=1", "__CMSIS_RTOS", "__MBED_CMSIS_RTOS_CM"],
         "Cortex-A9" : ["__CORTEX_A9", "ARM_MATH_CA9", "__FPU_PRESENT", "__CMSIS_RTOS", "__EVAL", "__MBED_CMSIS_RTOS_CA9"],
-        "Cortex-M23-NS": ["__CORTEX_M23", "ARM_MATH_ARMV8MBL", "__DOMAIN_NS=1", "__CMSIS_RTOS", "__MBED_CMSIS_RTOS_CM"],
+        "Cortex-M23-NS": ["__CORTEX_M23", "ARM_MATH_ARMV8MBL", "DOMAIN_NS=1", "__CMSIS_RTOS", "__MBED_CMSIS_RTOS_CM"],
         "Cortex-M23": ["__CORTEX_M23", "ARM_MATH_ARMV8MBL", "__CMSIS_RTOS", "__MBED_CMSIS_RTOS_CM"],
-        "Cortex-M33-NS": ["__CORTEX_M33", "ARM_MATH_ARMV8MML", "__DOMAIN_NS=1", "__CMSIS_RTOS", "__MBED_CMSIS_RTOS_CM"],
+        "Cortex-M33-NS": ["__CORTEX_M33", "ARM_MATH_ARMV8MML", "DOMAIN_NS=1", "__CMSIS_RTOS", "__MBED_CMSIS_RTOS_CM"],
         "Cortex-M33": ["__CORTEX_M33", "ARM_MATH_ARMV8MML", "__CMSIS_RTOS", "__MBED_CMSIS_RTOS_CM"],
-        "Cortex-M33F-NS": ["__CORTEX_M33", "ARM_MATH_ARMV8MML", "__DOMAIN_NS=1", "__FPU_PRESENT", "__CMSIS_RTOS", "__MBED_CMSIS_RTOS_CM"],
+        "Cortex-M33F-NS": ["__CORTEX_M33", "ARM_MATH_ARMV8MML", "DOMAIN_NS=1", "__FPU_PRESENT", "__CMSIS_RTOS", "__MBED_CMSIS_RTOS_CM"],
         "Cortex-M33F": ["__CORTEX_M33", "ARM_MATH_ARMV8MML", "__FPU_PRESENT", "__CMSIS_RTOS", "__MBED_CMSIS_RTOS_CM"],
     }