diff --git a/include/semphr.h b/include/semphr.h
index 7b44d78c05..69eb98c5ff 100644
--- a/include/semphr.h
+++ b/include/semphr.h
@@ -1157,6 +1157,7 @@ typedef QueueHandle_t SemaphoreHandle_t;
  * If xMutex is not a mutex type semaphore, or the mutex is available (not held
  * by a task), return NULL.
  *
+ * Note: On SMP systems, the return value may be invalidated by other core(s).
  */
 #if ( ( configUSE_MUTEXES == 1 ) && ( INCLUDE_xSemaphoreGetMutexHolder == 1 ) )
     #define xSemaphoreGetMutexHolderFromISR( xSemaphore )    xQueueGetMutexHolderFromISR( ( xSemaphore ) )