diff --git a/sonoff/user_config.h b/sonoff/user_config.h
index d46a295d7..357fe5fab 100644
--- a/sonoff/user_config.h
+++ b/sonoff/user_config.h
@@ -335,6 +335,7 @@
   #define CO2_HIGH             1200              // Above this CO2 value show red light (needs PWM or WS2812 RG(B) led and enable with SetOption18 1)
 #define USE_PMS5003                              // Add support for PMS5003 and PMS7003 particle concentration sensor (+1k3 code)
 #define USE_NOVA_SDS                             // Add support for SDS011 and SDS021 particle concentration sensor (+0k7 code)
+  #define WORKING_PERIOD       5                 // Working period of the SDS Sensor, Takes a reading every X Minutes
 #define USE_SERIAL_BRIDGE                        // Add support for software Serial Bridge (+0k8 code)
 //#define USE_SDM120                               // Add support for Eastron SDM120-Modbus energy meter (+1k7 code)
   #define SDM120_SPEED         9600              // SDM120-Modbus RS485 serial speed (default: 2400 baud)