diff --git a/components/libc/compilers/armlibc/syscalls.c b/components/libc/compilers/armlibc/syscalls.c
index 8addb3e163891243674ce784fdda023a54bcf18e..d17460b4137f6b8c05587a214f9a005a80ffb951 100644
--- a/components/libc/compilers/armlibc/syscalls.c
+++ b/components/libc/compilers/armlibc/syscalls.c
@@ -13,7 +13,6 @@
  *                             RT_USING_DFS is not defined
  * 2020-02-13     Meco Man     re-implement exit() and abort()
  * 2020-02-14     Meco Man     implement _sys_tmpnam()
- * 2020-02-25     Meco Man     add multithreaded protection
  */
 
 #include <string.h>
@@ -42,36 +41,6 @@ const char __stdin_name[]  = "STDIN";
 const char __stdout_name[] = "STDOUT";
 const char __stderr_name[] = "STDERR";
 
-#ifdef RT_USING_HEAP
-int _mutex_initialize(rt_mutex_t *m)
-{
-    *m = rt_mutex_create("_mutex_", RT_IPC_FLAG_PRIO);
-    if(*m == RT_NULL)
-    {
-        return 0;
-    }
-    else
-    {
-        return 1;
-    }
-}
-
-void _mutex_acquire(rt_mutex_t *m)
-{
-    rt_mutex_take(*m, RT_WAITING_FOREVER);
-}
-
-void _mutex_release(rt_mutex_t *m)
-{
-    rt_mutex_release(*m);
-}
-
-void _mutex_free(rt_mutex_t *m)
-{
-    rt_mutex_delete(*m);
-}
-#endif
-
 /**
  * required by fopen() and freopen().
  *
diff --git a/components/libc/compilers/dlib/rmtx.c b/components/libc/compilers/dlib/rmtx.c
deleted file mode 100644
index 69405c8f6a4d9104c2e4b53088a4314ab0a64817..0000000000000000000000000000000000000000
--- a/components/libc/compilers/dlib/rmtx.c
+++ /dev/null
@@ -1,60 +0,0 @@
-/*
- * Copyright (c) 2006-2018, RT-Thread Development Team
- *
- * SPDX-License-Identifier: Apache-2.0
- *
- * Change Logs:
- * Date           Author       Notes
- * 2015-01-28     Bernard      first version
- */
-#include <rtthread.h>
-#include <yfuns.h>
-
-/*
- * for IAR compiler, we recommand to define _DLIB_THREAD_SUPPORT
- * as 2 for dlib multi-thread support.
- */
-
-#if _DLIB_THREAD_SUPPORT
-typedef void* _Rmtx;
-void _Mtxinit(_Rmtx *m)
-{
-    rt_mutex_t mutex;
-
-    RT_ASSERT(m != RT_NULL);
-    
-    mutex = (rt_mutex_t)m;
-    rt_mutex_init(mutex, "iarMtx", RT_IPC_FLAG_FIFO);
-}
-
-void _Mtxdst(_Rmtx *m)
-{
-    rt_mutex_t mutex;
-
-    RT_ASSERT(m != RT_NULL);
-
-    mutex = (rt_mutex_t)m;
-    rt_mutex_detach(mutex);
-}
-
-void _Mtxlock(_Rmtx *m)
-{
-    rt_mutex_t mutex;
-
-    RT_ASSERT(m != RT_NULL);
-
-    mutex = (rt_mutex_t)m;
-    rt_mutex_take(mutex, RT_WAITING_FOREVER);
-}
-
-void _Mtxunlock(_Rmtx *m)
-{
-    rt_mutex_t mutex;
-
-    RT_ASSERT(m != RT_NULL);
-
-    mutex = (rt_mutex_t)m;
-    rt_mutex_release(mutex);
-}
-#endif
-