diff --git a/package/src/common/configure.ts b/package/src/common/configure.ts
index f8406df08b..a40b185fa8 100644
--- a/package/src/common/configure.ts
+++ b/package/src/common/configure.ts
@@ -18,13 +18,22 @@ import {
   configureDependency,
   kDependencies,
 } from "./dependencies/dependencies.ts";
-import { suggestUserBinPaths } from "../../../src/core/path.ts";
+import { suggestUserBinPaths, which } from "../../../src/core/path.ts";
 import { buildQuartoPreviewJs } from "./previewjs.ts";
 import { isWindows } from "../../../src/deno_ral/platform.ts";
 
 export async function configure(
   config: Configuration,
 ) {
+  // npm is required later for building quarto-preview.js (used by `quarto
+  // preview` live-reload). Check upfront to fail fast before downloading
+  // hundreds of MB of dependencies when npm is missing.
+  if ((await which("npm")) === undefined) {
+    throw new Error(
+      "npm not found on PATH. Please install Node.js (which provides npm) before running configure.",
+    );
+  }
+
   // Download dependencies
   for (const dependency of kDependencies) {
     const targetDir = join(