diff --git a/README.md b/README.md
index 1d9d0eb..ff0b56b 100644
--- a/README.md
+++ b/README.md
@@ -99,13 +99,21 @@ Wring schema of the old vending machine.
 Central controller software. Has a simple HTTP API for controlling output and
 checking the current fill status of each slot.
 
-Written in Go, must be compiled before use:
+The controller is written in Go, must be compiled before use:
 
 ```shell
 cd uncanny/
 go build ./cmd/uncanny
 ```
 
+Note that CGO is required because the source code makes use of the global
+`messages.h` C header file. If you need to cross-compile, use the following
+command:
+
+```shell
+GOARCH=arm GOOS=linux CGO_ENABLED=1 CC=arm-linux-gnueabi-gcc go build -o uncanny-linux-arm ./cmd/uncanny
+```
+
 The resulting `uncanny` executable should be running on the controlling
 Raspberry Pi. An example SystemD unit is provided in `server/uncanny.service`.
 Copy `uncanny` to `/usr/bin`, install the service file to