diff --git a/apps/serial-shell/serial-shell.c b/apps/serial-shell/serial-shell.c
index 96383bdb7..f33cd9aef 100644
--- a/apps/serial-shell/serial-shell.c
+++ b/apps/serial-shell/serial-shell.c
@@ -58,6 +58,8 @@ void
 shell_default_output(const char *text1, int len1, const char *text2, int len2)
 {
   int i;
+  
+  mcu_sleep_off();
   if(text1 == NULL) {
     text1 = "";
     len1 = 0;
@@ -76,6 +78,7 @@ shell_default_output(const char *text1, int len1, const char *text2, int len2)
     printf("%c", text2[i]);
   }
   printf("\r\n");
+  mcu_sleep_on();
 }
 /*---------------------------------------------------------------------------*/
 void
@@ -98,7 +101,9 @@ PROCESS_THREAD(serial_shell_process, ev, data)
 
   while(1) {
     PROCESS_WAIT_EVENT_UNTIL(ev == serial_line_event_message && data != NULL);
+    mcu_sleep_off();
     shell_input(data, strlen(data));
+    mcu_sleep_on();
   }
 
   PROCESS_END();