diff --git a/examples/system/console/components/cmd_system/cmd_system.c b/examples/system/console/components/cmd_system/cmd_system.c
index 1acb295250..26c36f9940 100644
--- a/examples/system/console/components/cmd_system/cmd_system.c
+++ b/examples/system/console/components/cmd_system/cmd_system.c
@@ -10,6 +10,7 @@
 #include <stdio.h>
 #include <string.h>
 #include <ctype.h>
+#include <unistd.h>
 #include "esp_log.h"
 #include "esp_console.h"
 #include "esp_system.h"
@@ -295,13 +296,13 @@ static int light_sleep(int argc, char **argv)
     if (io_count > 0) {
         ESP_ERROR_CHECK( esp_sleep_enable_gpio_wakeup() );
     }
-    if (CONFIG_ESP_CONSOLE_UART_NUM <= UART_NUM_1) {
+    if (CONFIG_ESP_CONSOLE_UART_NUM >= 0 && CONFIG_ESP_CONSOLE_UART_NUM <= UART_NUM_1) {
         ESP_LOGI(TAG, "Enabling UART wakeup (press ENTER to exit light sleep)");
         ESP_ERROR_CHECK( uart_set_wakeup_threshold(CONFIG_ESP_CONSOLE_UART_NUM, 3) );
         ESP_ERROR_CHECK( esp_sleep_enable_uart_wakeup(CONFIG_ESP_CONSOLE_UART_NUM) );
     }
     fflush(stdout);
-    uart_wait_tx_idle_polling(CONFIG_ESP_CONSOLE_UART_NUM);
+    fsync(fileno(stdout));
     esp_light_sleep_start();
     esp_sleep_wakeup_cause_t cause = esp_sleep_get_wakeup_cause();
     const char *cause_str;