diff --git a/src/mem.c b/src/mem.c
index ba080a5bcb..4aeae0b589 100644
--- a/src/mem.c
+++ b/src/mem.c
@@ -48,7 +48,7 @@
 #include <rtthread.h>
 
 /* #define RT_MEM_DEBUG */
-#define RT_MEM_STATS
+#define RT_MEM_STATS
 
 #if defined (RT_USING_HEAP) && defined (RT_USING_SMALL_MEM)
 #ifdef RT_USING_HOOK
@@ -109,11 +109,11 @@ static struct heap_mem *heap_end;
 static struct heap_mem *lfree;   /* pointer to the lowest free block */
 
 static struct rt_semaphore heap_sem;
-static rt_size_t mem_size_aligned;
-
+static rt_size_t mem_size_aligned;
+
 #ifdef RT_MEM_STATS
-static rt_size_t used_mem, max_mem;
-#endif
+static rt_size_t used_mem, max_mem;
+#endif
 
 static void plug_holes(struct heap_mem *mem)
 {
@@ -194,7 +194,7 @@ void rt_system_heap_init(void* begin_addr, void* end_addr)
 	rt_sem_init(&heap_sem, "heap", 1, RT_IPC_FLAG_FIFO);
 
 	/* initialize the lowest-free pointer to the start of the heap */
-	lfree = (struct heap_mem *)heap_ptr;
+	lfree = (struct heap_mem *)heap_ptr;
 }
 
 /**
@@ -277,10 +277,10 @@ void *rt_malloc(rt_size_t size)
 				if (mem2->next != mem_size_aligned)
 				{
 					((struct heap_mem *)&heap_ptr[mem2->next])->prev = ptr2;
-				}
-#ifdef RT_MEM_STATS
-				used_mem += (size + SIZEOF_STRUCT_MEM);
-				if (max_mem < used_mem) max_mem = used_mem;
+				}
+#ifdef RT_MEM_STATS
+				used_mem += (size + SIZEOF_STRUCT_MEM);
+				if (max_mem < used_mem) max_mem = used_mem;
 #endif
 			}
 			else
@@ -292,10 +292,10 @@ void *rt_malloc(rt_size_t size)
 				 * also can't move mem->next directly behind mem, since mem->next
 				 * will always be used at this point!
 				 */
-				mem->used = 1;
-#ifdef RT_MEM_STATS
-				used_mem += mem->next - ((rt_uint8_t*)mem - heap_ptr);
-				if (max_mem < used_mem) max_mem = used_mem;
+				mem->used = 1;
+#ifdef RT_MEM_STATS
+				used_mem += mem->next - ((rt_uint8_t*)mem - heap_ptr);
+				if (max_mem < used_mem) max_mem = used_mem;
 #endif
 			}
 
@@ -342,6 +342,7 @@ void *rt_realloc(void *rmem, rt_size_t newsize)
 	rt_size_t size;
 	rt_size_t ptr, ptr2;
 	struct heap_mem *mem, *mem2;
+	void* nmem;
 
 	/* alignment size */
 	newsize = RT_ALIGN(newsize, RT_ALIGN_SIZE);
@@ -369,10 +370,10 @@ void *rt_realloc(void *rmem, rt_size_t newsize)
 	size = mem->next - ptr - SIZEOF_STRUCT_MEM;
 
 	if (newsize + SIZEOF_STRUCT_MEM + MIN_SIZE < size)
-	{
-#if MEM_STATS
-  		used_mem -= (size - newsize);
-#endif /* MEM_STATS */
+	{
+#if MEM_STATS
+  		used_mem -= (size - newsize);
+#endif /* MEM_STATS */
 
 		ptr2 = ptr + SIZEOF_STRUCT_MEM + newsize;
 		mem2 = (struct heap_mem *)&heap_ptr[ptr2];
@@ -394,12 +395,12 @@ void *rt_realloc(void *rmem, rt_size_t newsize)
 	rt_sem_release(&heap_sem);
 
 	/* expand memory */
-	mem2 = rt_malloc(newsize);
-	rt_memcpy(mem2, mem, size);
+	nmem = rt_malloc(newsize);
+	rt_memcpy(nmem, rmem, size);
 
-	rt_free(mem);
+	rt_free(rmem);
 
-	return mem2;
+	return nmem;
 }
 
 /**
@@ -475,16 +476,16 @@ void rt_free(void *rmem)
 	{
 		/* the newly freed struct is now the lowest */
 		lfree = mem;
-	}
+	}
 
-#ifdef RT_MEM_STATS
-	used_mem -= (mem->next - ((rt_uint8_t*)mem - heap_ptr));
-#endif
+#ifdef RT_MEM_STATS
+	used_mem -= (mem->next - ((rt_uint8_t*)mem - heap_ptr));
+#endif
 
 	/* finally, see if prev or next are free also */
 	plug_holes(mem);
 	rt_sem_release(&heap_sem);
-}
+}
 
 #ifdef RT_MEM_STATS
 #ifdef RT_USING_FINSH
@@ -497,7 +498,7 @@ void list_mem()
 }
 FINSH_FUNCTION_EXPORT(list_mem, list memory usage information)
 #endif
-#endif
+#endif
 
 /*@}*/