diff --git a/BUILD.md b/BUILD.md
index 59674c0..25fd30e 100644
--- a/BUILD.md
+++ b/BUILD.md
@@ -42,6 +42,8 @@ Create a .rpm:
 
 ## macOS
 
+Install [Docker Desktop](https://www.docker.com/products/docker-desktop).
+
 Install python@3.9 from Homebrew:
 
 ```
@@ -83,6 +85,8 @@ The output is in the `dist` folder.
 
 ## Windows
 
+Install [Docker Desktop](https://www.docker.com/products/docker-desktop).
+
 These instructions include adding folders to the path in Windows. To do this, go to Start and type "advanced system settings", and open "View advanced system settings" in the Control Panel. Click Environment Variables. Under "System variables" double-click on Path. From there you can add and remove folders that are available in the PATH.
 
 Download Python 3.9.0, 32-bit (x86) from https://www.python.org/downloads/release/python-390/. I downloaded python-3.9.0.exe. When installing it, make sure to check the "Add Python 3.9 to PATH" checkbox on the first page of the installer.