diff --git a/rtos/TARGET_CORTEX/rtx5/RTX/Source/rtx_lib.c b/rtos/TARGET_CORTEX/rtx5/RTX/Source/rtx_lib.c
index b08b04d99b..58f67f375c 100644
--- a/rtos/TARGET_CORTEX/rtx5/RTX/Source/rtx_lib.c
+++ b/rtos/TARGET_CORTEX/rtx5/RTX/Source/rtx_lib.c
@@ -374,7 +374,7 @@ __attribute__((section(".rodata"))) =
   0U,
 #endif
   { &os_isr_queue[0], (uint16_t)(sizeof(os_isr_queue)/sizeof(void *)), 0U },
-  { 
+  {
     // Memory Pools (Variable Block Size)
 #if ((OS_THREAD_OBJ_MEM != 0) && (OS_THREAD_USER_STACK_SIZE != 0))
     &os_thread_stack[0], sizeof(os_thread_stack),
@@ -407,7 +407,7 @@ __attribute__((section(".rodata"))) =
 #endif
     &os_mpi_thread,
 #else
-    NULL, 
+    NULL,
     NULL,
 #endif
 #if (OS_TIMER_OBJ_MEM != 0)
@@ -490,7 +490,7 @@ __asm void os_cb_sections_wrapper (void) {
                 EXTERN  ||.bss.os.mempool.cb$$Limit||   [WEAK]
                 EXTERN  ||.bss.os.msgqueue.cb$$Base||   [WEAK]
                 EXTERN  ||.bss.os.msgqueue.cb$$Limit||  [WEAK]
-  
+
                 AREA    ||.rodata||, DATA, READONLY
                 EXPORT  os_cb_sections
 os_cb_sections
@@ -676,11 +676,12 @@ typedef void *mutex;
 //lint -e818 "Pointer 'm' could be declared as pointing to const"
 
 // Initialize mutex
+#if !defined(__ARMCC_VERSION) || __ARMCC_VERSION < 6010050
 __USED
+#endif
 int _mutex_initialize(mutex *m);
-int _mutex_initialize(mutex *m) {
+__WEAK int _mutex_initialize(mutex *m) {
   int result;
-
   *m = osMutexNew(NULL);
   if (*m != NULL) {
     result = 1;
@@ -692,8 +693,10 @@ int _mutex_initialize(mutex *m) {
 }
 
 // Acquire mutex
+#if !defined(__ARMCC_VERSION) || __ARMCC_VERSION < 6010050
 __USED
-void _mutex_acquire(mutex *m);
+#endif
+__WEAK void _mutex_acquire(mutex *m);
 void _mutex_acquire(mutex *m) {
   if (os_kernel_is_active() != 0U) {
     (void)osMutexAcquire(*m, osWaitForever);
@@ -701,8 +704,10 @@ void _mutex_acquire(mutex *m) {
 }
 
 // Release mutex
+#if !defined(__ARMCC_VERSION) || __ARMCC_VERSION < 6010050
 __USED
-void _mutex_release(mutex *m);
+#endif
+__WEAK void _mutex_release(mutex *m);
 void _mutex_release(mutex *m) {
   if (os_kernel_is_active() != 0U) {
     (void)osMutexRelease(*m);
@@ -710,8 +715,10 @@ void _mutex_release(mutex *m) {
 }
 
 // Free mutex
+#if !defined(__ARMCC_VERSION) || __ARMCC_VERSION < 6010050
 __USED
-void _mutex_free(mutex *m);
+#endif
+__WEAK void _mutex_free(mutex *m);
 void _mutex_free(mutex *m) {
   (void)osMutexDelete(*m);
 }