diff --git a/src/memheap.c b/src/memheap.c
index 71e43580f4f580d825e036dbb2cb7b3f4f0adf07..85f48991166bd0489b6a771bd31deb9cd3f89fcd 100644
--- a/src/memheap.c
+++ b/src/memheap.c
@@ -38,7 +38,7 @@
 #define MEMITEM_SIZE(item)      ((rt_ubase_t)item->next - (rt_ubase_t)item - RT_MEMHEAP_SIZE)
 #define MEMITEM(ptr)            (struct rt_memheap_item*)((rt_uint8_t*)ptr - RT_MEMHEAP_SIZE)
 
-static void _remove_next_ptr(struct rt_memheap_item *next_ptr)
+static void _remove_next_ptr(volatile struct rt_memheap_item *next_ptr)
 {
     /* Fix the crash problem after opening Oz optimization on ac6  */
     /* Fix IAR compiler warning  */
@@ -392,7 +392,7 @@ void *rt_memheap_realloc(struct rt_memheap *heap, void *ptr, rt_size_t newsize)
     if (newsize > oldsize)
     {
         void *new_ptr;
-        struct rt_memheap_item *next_ptr;
+        volatile struct rt_memheap_item *next_ptr;
 
         if (heap->locked == RT_FALSE)
         {
@@ -980,6 +980,8 @@ int memheaptrace(int argc, char *argv[])
                 rt_kprintf("%5d", block_size);
             else if (block_size < 1024 * 1024)
                 rt_kprintf("%4dK", block_size / 1024);
+            else if (block_size < 1024 * 1024 * 100)
+                rt_kprintf("%2d.%dM", block_size / (1024 * 1024),  (block_size % (1024 * 1024) * 10) / (1024 * 1024));
             else
                 rt_kprintf("%4dM", block_size / (1024 * 1024));
             /* dump thread name */