diff --git a/platformio.ini b/platformio.ini
index 87b9da9..25c7087 100644
--- a/platformio.ini
+++ b/platformio.ini
@@ -9,7 +9,7 @@
 ; https://docs.platformio.org/page/projectconf.html
 
 [env]
-platform = espressif8266
+platform = espressif8266@4.2.1
 framework = arduino
 monitor_speed = 115200
 custom_prog_version = 1.1.4