diff --git a/PICOCALC.md b/PICOCALC.md
index 0f2ab63..f8450fc 100644
--- a/PICOCALC.md
+++ b/PICOCALC.md
@@ -2,6 +2,9 @@
 
 This code runs on a PicoCalc with a Pico 2W.
 
+In order to build this, copy the libraries (in the `libraries` directory)
+to `${ARDUINO_HOME}/libraries`.
+
 Future work:
 
 - Fix autorestore: currently, the image must be `(load-image)`'d