diff --git a/Firmware/platformio.ini b/Firmware/platformio.ini
index 1ad995c703c90bdc1d9772a45b2c261a0084ba79..28e3387d2bf3e4a865357cff6ef9c77fd6ccf889 100644
--- a/Firmware/platformio.ini
+++ b/Firmware/platformio.ini
@@ -20,9 +20,12 @@ lib_deps = ArduinoJson@5.13.4
 	https://github.com/boblemaire/asyncHTTPrequest@1.2.2
 
 [env:iotawatt]
-platform = espressif8266@2.4.0
+; ESP8266 Arduino Core 3.1.2 with NONOS SDK 3.0.5.
+platform = espressif8266@4.2.1
+platform_packages = platformio/framework-arduinoespressif8266@3.30102.0
 build_unflags = -Wall
 build_flags = -D PIO_FRAMEWORK_ARDUINO_LWIP2_HIGHER_BANDWIDTH
+	-D PIO_FRAMEWORK_ARDUINO_ESPRESSIF_SDK305
 board = esp12e
 framework = arduino
 lib_deps = ${common.lib_deps}