diff --git a/previewhtml-sample/README.md b/previewhtml-sample/README.md
index afcfba59..105f3e19 100644
--- a/previewhtml-sample/README.md
+++ b/previewhtml-sample/README.md
@@ -22,5 +22,6 @@ The purpose of the extension is to show a preview of the properties in the decla
 
 # How to run locally
 
+* `npm install`
 * `npm run compile` to start the compiler in watch mode
-* open this folder in VS Code and press `F5`
\ No newline at end of file
+* open this folder in VS Code and press `F5`