diff --git a/README.md b/README.md
index cdf6cb879..b5ed5d4f9 100644
--- a/README.md
+++ b/README.md
@@ -95,6 +95,7 @@ rvm install ruby-3.3.2
 Next, you can build & serve the documentation preview:
 
 ```shell script
+npm install           # This needs to be run once for initialization
 npm run serve-preview
 ```