diff --git a/demos/ARMCM4-STM32F303-DISCOVERY/chconf.h b/demos/ARMCM4-STM32F303-DISCOVERY/chconf.h
index 84efe76f6..0886d559c 100644
--- a/demos/ARMCM4-STM32F303-DISCOVERY/chconf.h
+++ b/demos/ARMCM4-STM32F303-DISCOVERY/chconf.h
@@ -90,16 +90,9 @@
 /**
  * @brief   Idle thread automatic spawn suppression.
  * @details When this option is activated the function @p chSysInit()
- *          does not spawn the idle thread automatically. The application has
- *          then the responsibility to do one of the following:
- *          - Spawn a custom idle thread at priority @p IDLEPRIO.
- *          - Change the main() thread priority to @p IDLEPRIO then enter
- *            an endless loop. In this scenario the @p main() thread acts as
- *            the idle thread.
- *          .
- * @note    Unless an idle thread is spawned the @p main() thread must not
- *          enter a sleep state.
- */
+ *          does not spawn the idle thread. The application @p main()
+ *          function becomes the idle thread and must implement an
+ *          infinite loop. */
 #if !defined(CH_CFG_NO_IDLE_THREAD) || defined(__DOXYGEN__)
 #define CH_CFG_NO_IDLE_THREAD               FALSE
 #endif
diff --git a/os/kernel/src/chsys.c b/os/kernel/src/chsys.c
index 61157b1b9..7a6d3ea20 100644
--- a/os/kernel/src/chsys.c
+++ b/os/kernel/src/chsys.c
@@ -115,8 +115,14 @@ void chSysInit(void) {
   _trace_init();
 #endif
 
+#if !CH_CFG_NO_IDLE_THREAD
   /* Now this instructions flow becomes the main thread.*/
   setcurrp(_thread_init(&mainthread, NORMALPRIO));
+#else
+  /* Now this instructions flow becomes the main thread.*/
+  setcurrp(_thread_init(&mainthread, IDLEPRIO));
+#endif
+
   currp->p_state = CH_STATE_CURRENT;
 #if CH_DBG_ENABLE_STACK_CHECK
   /* This is a special case because the main thread thread_t structure is not