diff --git a/readme.md b/readme.md
index 41ce7ec..270a007 100755
--- a/readme.md
+++ b/readme.md
@@ -8,4 +8,8 @@ additional software in ROM. In future, more modules are planned:
  - A command line shell
  - A 65816 macro assembler
  - A text editor
- - Your idea here!
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+ - Your idea here!
+
+ To build the kernel and ROM image, you will need the Calypsi toolchain (https://calypsi.cc),
+ as well as GNU make. To build the fonts in the ROM image from the image file,
+ you will need Aseprite (https://www.aseprite.org).
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