diff --git a/hal/targets/hal/TARGET_STM/TARGET_STM32F3/gpio_object.h b/hal/targets/hal/TARGET_STM/TARGET_STM32F3/gpio_object.h
index 3b71f21189..b88f11fb99 100644
--- a/hal/targets/hal/TARGET_STM/TARGET_STM32F3/gpio_object.h
+++ b/hal/targets/hal/TARGET_STM/TARGET_STM32F3/gpio_object.h
@@ -44,8 +44,8 @@ typedef struct {
     PinName  pin;
     uint32_t mask;
     __IO uint32_t *reg_in;
-    __IO uint16_t *reg_set;
-    __IO uint16_t *reg_clr;
+    __IO uint32_t *reg_set;
+    __IO uint32_t *reg_clr;
 } gpio_t;
 
 static inline void gpio_write(gpio_t *obj, int value)
diff --git a/rtos/rtx/TARGET_CORTEX_M/RTX_CM_lib.h b/rtos/rtx/TARGET_CORTEX_M/RTX_CM_lib.h
index f2b1ab4228..2ffa9cc57d 100755
--- a/rtos/rtx/TARGET_CORTEX_M/RTX_CM_lib.h
+++ b/rtos/rtx/TARGET_CORTEX_M/RTX_CM_lib.h
@@ -534,14 +534,20 @@ extern uint32_t          __end__[];
 #define HEAP_START      (__end__)
 #elif defined(__ICCARM__)
 #pragma section="HEAP"
-#define HEAP_START     (void *)__section_begin("HEAP")
+#define HEAP_END  (void *)__section_end("HEAP")
 #endif
 
 void set_main_stack(void) {
     uint32_t interrupt_stack_size = ((uint32_t)OS_MAINSTKSIZE * 4);
+#if defined(__ICCARM__)
+	/* For IAR heap is defined  .icf file */
+	uint32_t main_stack_size = ((uint32_t)INITIAL_SP - (uint32_t)HEAP_END) - interrupt_stack_size;
+#else
+	/* For ARM , uARM, or GCC_ARM , heap can grow and reach main stack */
     uint32_t heap_plus_stack_size = ((uint32_t)INITIAL_SP - (uint32_t)HEAP_START) - interrupt_stack_size;
     // Main thread's stack is 1/4 of the heap
-    uint32_t main_stack_size = heap_plus_stack_size / 4;
+    uint32_t main_stack_size = heap_plus_stack_size/4;
+#endif
     // The main thread must be 4 byte aligned
     uint32_t main_stack_start = ((uint32_t)INITIAL_SP - interrupt_stack_size - main_stack_size) & ~0x7;