diff --git a/Arduino_Sketch/platformio.ini b/Arduino_Sketch/platformio.ini
index 7b8b0a9..5d67d3b 100644
--- a/Arduino_Sketch/platformio.ini
+++ b/Arduino_Sketch/platformio.ini
@@ -9,7 +9,7 @@
 ; https://docs.platformio.org/page/projectconf.html
 
 [env:d1_mini]
-platform = espressif8266
+platform = https://github.com/platformio/platform-espressif8266.git @ ^3.1.0
 board = d1_mini
 framework = arduino
 board_build.f_cpu = 160000000L