diff --git a/README.md b/README.md
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--- a/README.md
+++ b/README.md
@@ -6,7 +6,7 @@ Communicate with the atPlatform using a Raspberry Pi Pico W.
 Developed with [MicroPython](https://micropython.org/).
 
 ## Usage
-- Install [this](https://github.com/atsign-foundation/at_pico_w/blob/feature/aes-pem-rsa/custom_firmware.uf2) custom firmware in your Pico W.
+- Install the latest `firmware.uf2` onto your Pico W from [atsign-foundation/micropython Releases](https://github.com/atsign-foundation/micropython/releases), as this is patched to enable AES CTR, which is used by atSigns.
 - Fill all the fields of the `settings.json` file (ssid/passw of your Wi-Fi network and atSign). 
 - Download [Thonny IDE](https://thonny.org/) and place all the files of this repository in the Pico W file system.
 - Place your `.atKeys` file in the `~/keys/` directory (if the folder doesn't exist, create it manually)
diff --git a/custom_firmware.uf2 b/custom_firmware.uf2
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Binary files a/custom_firmware.uf2 and /dev/null differ