diff --git a/firmware/platformio.ini b/firmware/platformio.ini
index 082706d..b3c55f8 100644
--- a/firmware/platformio.ini
+++ b/firmware/platformio.ini
@@ -47,5 +47,5 @@ lib_deps =
     arduino-libraries/NTPClient
     knolleary/PubSubClient
     hideakitai/MsgPack
-    bblanchon/ArduinoJson
+    bblanchon/ArduinoJson@6.20.1
 	; END   Azure IoT dependencies	
\ No newline at end of file