diff --git a/packages/webpack-cli/src/webpack-cli.ts b/packages/webpack-cli/src/webpack-cli.ts
index d225f47ad81..5c69dbb57a3 100644
--- a/packages/webpack-cli/src/webpack-cli.ts
+++ b/packages/webpack-cli/src/webpack-cli.ts
@@ -57,8 +57,14 @@ const { pathToFileURL } = require("url");
 const util = require("util");
 const { program, Option } = require("commander");
 
-const WEBPACK_PACKAGE = process.env.WEBPACK_PACKAGE || "webpack";
-const WEBPACK_DEV_SERVER_PACKAGE = process.env.WEBPACK_DEV_SERVER_PACKAGE || "webpack-dev-server";
+const WEBPACK_PACKAGE_IS_CUSTOM = !!process.env.WEBPACK_PACKAGE;
+const WEBPACK_PACKAGE = WEBPACK_PACKAGE_IS_CUSTOM
+  ? (process.env.WEBPACK_PACKAGE as string)
+  : "webpack";
+const WEBPACK_DEV_SERVER_PACKAGE_IS_CUSTOM = !!process.env.WEBPACK_DEV_SERVER_PACKAGE;
+const WEBPACK_DEV_SERVER_PACKAGE = WEBPACK_DEV_SERVER_PACKAGE_IS_CUSTOM
+  ? (process.env.WEBPACK_DEV_SERVER_PACKAGE as string)
+  : "webpack-dev-server";
 
 interface Information {
   Binaries?: string[];
@@ -566,12 +572,12 @@ class WebpackCLI implements IWebpackCLI {
         let skipInstallation = false;
 
         // Allow to use `./path/to/webpack.js` outside `node_modules`
-        if (dependency === WEBPACK_PACKAGE && fs.existsSync(WEBPACK_PACKAGE)) {
+        if (dependency === WEBPACK_PACKAGE && WEBPACK_PACKAGE_IS_CUSTOM) {
           skipInstallation = true;
         }
 
         // Allow to use `./path/to/webpack-dev-server.js` outside `node_modules`
-        if (dependency === WEBPACK_DEV_SERVER_PACKAGE && fs.existsSync(WEBPACK_PACKAGE)) {
+        if (dependency === WEBPACK_DEV_SERVER_PACKAGE && WEBPACK_DEV_SERVER_PACKAGE_IS_CUSTOM) {
           skipInstallation = true;
         }