diff --git a/platformio.ini b/platformio.ini
index 84200955..cb1e42e8 100644
--- a/platformio.ini
+++ b/platformio.ini
@@ -80,6 +80,7 @@ arduino_core_2_6_2 = espressif8266@2.3.1
 arduino_core_stage = https://github.com/platformio/platform-espressif8266.git#feature/stage
 platform = ${common:esp8266.arduino_core_2_6_2}
 build_flags =
+  -D ESP8266
   -D PIO_FRAMEWORK_ARDUINO_LWIP2_HIGHER_BANDWIDTH
   -Wl,-Teagle.flash.4m1m.ld  ;;;; Required for core > v2.5.0 or staging version 4MB Flash 3MB SPIFFs