diff --git a/platform/mbed_application.c b/platform/mbed_application.c
index 75657f69e7..768e9c62df 100644
--- a/platform/mbed_application.c
+++ b/platform/mbed_application.c
@@ -48,12 +48,21 @@ static void powerdown_nvic()
     int i;
     int j;
 
+#if defined(__CORTEX_M23)
+    // M23 doesn't support ICTR and supports up to 240 external interrupts.
+    isr_groups_32 = 8;
+#else
     isr_groups_32 = ((SCnSCB->ICTR & SCnSCB_ICTR_INTLINESNUM_Msk) >> SCnSCB_ICTR_INTLINESNUM_Pos) + 1;
+#endif
     for (i = 0; i < isr_groups_32; i++) {
         NVIC->ICER[i] = 0xFFFFFFFF;
         NVIC->ICPR[i] = 0xFFFFFFFF;
         for (j = 0; j < 8; j++) {
+#if defined(__CORTEX_M23)
+            NVIC->IPR[i * 8 + j] = 0x00000000;
+#else
             NVIC->IP[i * 8 + j] = 0x00000000;
+#endif
         }
     }
 }
@@ -68,6 +77,11 @@ static void powerdown_scb(uint32_t vtor)
     SCB->AIRCR = 0x05FA | 0x0000;
     SCB->SCR = 0x00000000;
     // SCB->CCR     - Implementation defined value
+#if defined(__CORTEX_M23)
+    for (i = 0; i < 2; i++) {
+        SCB->SHPR[i] = 0x00;
+    }
+#else
     for (i = 0; i < 12; i++) {
 #if defined(__CORTEX_M7)
         SCB->SHPR[i] = 0x00;
@@ -75,11 +89,15 @@ static void powerdown_scb(uint32_t vtor)
         SCB->SHP[i] = 0x00;
 #endif
     }
+#endif
     SCB->SHCSR = 0x00000000;
+#if defined(__CORTEX_M23)
+#else
     SCB->CFSR = 0xFFFFFFFF;
     SCB->HFSR = SCB_HFSR_DEBUGEVT_Msk | SCB_HFSR_FORCED_Msk | SCB_HFSR_VECTTBL_Msk;
     SCB->DFSR = SCB_DFSR_EXTERNAL_Msk | SCB_DFSR_VCATCH_Msk |
                 SCB_DFSR_DWTTRAP_Msk | SCB_DFSR_BKPT_Msk | SCB_DFSR_HALTED_Msk;
+#endif
     // SCB->MMFAR   - Implementation defined value
     // SCB->BFAR    - Implementation defined value
     // SCB->AFSR    - Implementation defined value
@@ -107,7 +125,9 @@ __asm static void start_new_application(void *sp, void *pc)
 void start_new_application(void *sp, void *pc)
 {
     __asm volatile (
-        "mov    r2, #0      \n"
+        "movw   r2, #0      \n" // Fail to compile "mov r2, #0" with ARMC6. Replace with MOVW.
+                                // We needn't "movt r2, #0" immediately following because MOVW
+                                // will zero-extend the 16-bit immediate.
         "msr    control, r2 \n" // Switch to main stack
         "mov    sp, %0      \n"
         "msr    primask, r2 \n" // Enable interrupts
diff --git a/platform/mbed_application.h b/platform/mbed_application.h
index 43b4813f75..d02ac67651 100644
--- a/platform/mbed_application.h
+++ b/platform/mbed_application.h
@@ -19,7 +19,8 @@
 
 #include<stdint.h>
 
-#if defined(__CORTEX_M3) || defined(__CORTEX_M4) || defined(__CORTEX_M7)
+#if defined(__CORTEX_M3) || defined(__CORTEX_M4) || defined(__CORTEX_M7)\
+    || defined(__CORTEX_M23)
 #define MBED_APPLICATION_SUPPORT 1
 #else
 #define MBED_APPLICATION_SUPPORT 0