diff --git a/README.md b/README.md
index f34a693c7f12727007d21d819687d5fa315af5d9..d424a5c5729285016dd48f5c59cec84b7f45beea 100644
--- a/README.md
+++ b/README.md
@@ -66,6 +66,18 @@ Standard ESP-IDF project machinery present and working. You can run `idf.py` fro
 
 ### Building
 
+Prepare build:
+
+```
+$ cd micropython/
+$ make -C mpy-cross
+$ cd ports/esp32
+$ make submodules
+$ cd ../../../
+```
+
+Build normally with idf.py:
+
 ```
 $ idf.py build
 ```