diff --git a/sonoff/sonoff.h b/sonoff/sonoff.h
index 228765a00..42f71e0b2 100644
--- a/sonoff/sonoff.h
+++ b/sonoff/sonoff.h
@@ -130,6 +130,8 @@ const uint32_t SERIAL_POLLING = 100;        // Serial receive polling in ms
 const uint32_t ZIGBEE_POLLING = 100;        // Serial receive polling in ms
 const uint8_t MAX_STATUS = 11;              // Max number of status lines
 
+const uint32_t START_VALID_TIME = 1451602800;  // Time is synced and after 2016-01-01
+
 const uint32_t DRIVER_BOOT_DELAY = 1;       // Number of milliseconds to retard driver cycles during boot-up time to reduce overall CPU load whilst Wifi is connecting
 const uint32_t LOOP_SLEEP_DELAY = 50;       // Lowest number of milliseconds to go through the main loop using delay when needed