diff --git a/docs/os-instructions.md b/docs/os-instructions.md
index 828c6e1..d895330 100644
--- a/docs/os-instructions.md
+++ b/docs/os-instructions.md
@@ -32,9 +32,9 @@ and run UPIWIN successfully.  This document describes the process.
 ## Installing Libraries for UPIWIN
 
 1. Use `sudo -i` to get a root command prompt.
-2. Execute the command to install packaged libraries:
+2. Execute the command to install packaged libraries and utilities:
 
-    apt install python3-dev libfreetype6-dev libpng-dev ttf-mscorefonts-installer
+    apt install python3-dev libfreetype6-dev libpng-dev libzip-dev ttf-mscorefonts-installer zip
 
 3. Execute the commands to install the BCM2835 library: