diff --git a/tools/toolchains/__init__.py b/tools/toolchains/__init__.py
index 2a63068b79..d5e810879a 100644
--- a/tools/toolchains/__init__.py
+++ b/tools/toolchains/__init__.py
@@ -335,8 +335,10 @@ class mbedToolchain:
         "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": ["__CORTEX_M23", "ARM_MATH_ARMV8MBL", "__CMSIS_RTOS", "__MBED_CMSIS_RTOS_CM"],
-        "Cortex-M33-NS": ["__CORTEX_M33", "ARM_MATH_ARMV8MML", "__DOMAIN_NS=1", "__FPU_PRESENT", "__CMSIS_RTOS", "__MBED_CMSIS_RTOS_CM"],
-        "Cortex-M33": ["__CORTEX_M33", "ARM_MATH_ARMV8MML", "__FPU_PRESENT", "__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": ["__CORTEX_M33", "ARM_MATH_ARMV8MML", "__FPU_PRESENT", "__CMSIS_RTOS", "__MBED_CMSIS_RTOS_CM"],
     }
 
     MBED_CONFIG_FILE_NAME="mbed_config.h"
diff --git a/tools/toolchains/gcc.py b/tools/toolchains/gcc.py
index 2543f4a89e..3a7f8356ce 100644
--- a/tools/toolchains/gcc.py
+++ b/tools/toolchains/gcc.py
@@ -48,21 +48,20 @@ class GCC(mbedToolchain):
             self.flags["ld"].append("--specs=nano.specs")
 
         if target.core == "Cortex-M0+":
-            cpu = "cortex-m0plus"
-        elif target.core == "Cortex-M4F":
-            cpu = "cortex-m4"
-        elif target.core == "Cortex-M7F":
-            cpu = "cortex-m7"
-        elif target.core == "Cortex-M7FD":
-            cpu = "cortex-m7"
-        elif target.core == "Cortex-M23-NS":
-            cpu = "cortex-m23"
-        elif target.core == "Cortex-M33-NS":
-            cpu = "cortex-m33"
+            self.cpu = ["-mcpu=cortex-m0plus"]
+        elif target.core.startswith("Cortex-M4"):
+            self.cpu = ["-mcpu=cortex-m4"]
+        elif target.core.startswith("Cortex-M7"):
+            self.cpu = ["-mcpu=cortex-m7"]
+        elif target.core.startswith("Cortex-M23"):
+            self.cpu = ["-mcpu=cortex-m23"]
+        elif target.core.startswith("Cortex-M33F"):
+            self.cpu = ["-mcpu=cortex-m33"]
+        elif target.core.startswith("Cortex-M33"):
+            self.cpu = ["-march=armv8-m.main"]
         else:
-            cpu = target.core.lower()
+            self.cpu = ["-mcpu={}".format(target.core.lower())]
 
-        self.cpu = ["-mcpu=%s" % cpu]
         if target.core.startswith("Cortex-M"):
             self.cpu.append("-mthumb")
 
@@ -85,7 +84,9 @@ class GCC(mbedToolchain):
             self.cpu.append("-mfloat-abi=hard")
             self.cpu.append("-mno-unaligned-access")
 
-        if target.core == "Cortex-M23" or target.core == "Cortex-M33":
+        if ((target.core.startswith("Cortex-M23") or
+             target.core.startswith("Cortex-M33")) and
+            not target.core.endswith("-NS")):
             self.cpu.append("-mcmse")
         elif target.core == "Cortex-M23-NS" or target.core == "Cortex-M33-NS":
              self.flags["ld"].append("-D__DOMAIN_NS=1")