diff --git a/demos/STM32/HAL-STM32F407-DISCOVERY/main.c b/demos/STM32/HAL-STM32F407-DISCOVERY/main.c
index a59c0b8ff..b9359ee4c 100644
--- a/demos/STM32/HAL-STM32F407-DISCOVERY/main.c
+++ b/demos/STM32/HAL-STM32F407-DISCOVERY/main.c
@@ -28,6 +28,11 @@ int main(void) {
    */
   halInit();
 
+  /*
+   * Enabling interrupts, initialization done.
+   */
+  osalSysEnable();
+
   /*
    * Activates the serial driver 2 using the driver default configuration.
    * PA2(TX) and PA3(RX) are routed to USART2.
@@ -41,6 +46,8 @@ int main(void) {
    * a shell respawn upon its termination.
    */
   while (true) {
+    chnWriteTimeout(&SD2, (uint8_t *)"Hello World!\r\n", 14, TIME_INFINITE);
+
     palSetPad(GPIOD, GPIOD_LED3);       /* Orange.  */
     osalThreadSleepMilliseconds(500);
     palClearPad(GPIOD, GPIOD_LED3);     /* Orange.  */