diff --git a/examples/timerbot.py b/examples/timerbot.py
index c900a273f..8d28ae592 100644
--- a/examples/timerbot.py
+++ b/examples/timerbot.py
@@ -43,7 +43,8 @@ def set(bot, update, args):
     try:
         # args[0] should contain the time for the timer in seconds
         due = int(args[0])
-
+        if due < 0:
+                bot.sendMessage(chat_id,text='Sorry we can not go back to future!')
         def alarm(bot):
             """ Inner function to send the alarm message """
             bot.sendMessage(chat_id, text='Beep!')