diff --git a/tools/webpack/blocks.js b/tools/webpack/blocks.js
index 94b5cb57b2272..91e2cfafbdf84 100644
--- a/tools/webpack/blocks.js
+++ b/tools/webpack/blocks.js
@@ -1,7 +1,6 @@
 /**
  * External dependencies
  */
-const { DefinePlugin } = require( 'webpack' );
 const CopyWebpackPlugin = require( 'copy-webpack-plugin' );
 
 /**
@@ -12,7 +11,7 @@ const DependencyExtractionPlugin = require( '@wordpress/dependency-extraction-we
 /**
  * Internal dependencies
  */
-const { normalizeJoin, stylesTransform, baseConfig, baseDir } = require( './shared' );
+const { baseDir, getBaseConfig, normalizeJoin, stylesTransform } = require( './shared' );
 const {
 	isDynamic,
 	toDirectoryName,
@@ -62,8 +61,9 @@ module.exports = function( env = { environment: 'production', watch: false, buil
 		noErrorOnMissing: true,
 	} ) );
 
+	const baseConfig = getBaseConfig( env );
 	const config = {
-		...baseConfig( env ),
+		...baseConfig,
 		entry: {
 			'navigation/view': normalizeJoin( baseDir, 'node_modules/@wordpress/block-library/build-module/navigation/view' ),
 			'image/view': normalizeJoin( baseDir, 'node_modules/@wordpress/block-library/build-module/image/view' ),
@@ -127,13 +127,7 @@ module.exports = function( env = { environment: 'production', watch: false, buil
 			],
 		},
 		plugins: [
-			new DefinePlugin( {
-				// Inject the `IS_GUTENBERG_PLUGIN` global, used for feature flagging.
-				'process.env.IS_GUTENBERG_PLUGIN': false,
-				'process.env.FORCE_REDUCED_MOTION': JSON.stringify(
-					process.env.FORCE_REDUCED_MOTION,
-				),
-			} ),
+			...baseConfig.plugins,
 			new DependencyExtractionPlugin( {
 				injectPolyfill: false,
 				useDefaults: false,
diff --git a/tools/webpack/packages.js b/tools/webpack/packages.js
index 65747bdf8e2ba..783f5b3321953 100644
--- a/tools/webpack/packages.js
+++ b/tools/webpack/packages.js
@@ -1,7 +1,6 @@
 /**
  * External dependencies
  */
-const { DefinePlugin } = require( 'webpack' );
 const CopyWebpackPlugin = require( 'copy-webpack-plugin' );
 const LiveReloadPlugin = require( 'webpack-livereload-plugin' );
 const UglifyJS = require( 'uglify-js' );
@@ -17,7 +16,7 @@ const DependencyExtractionPlugin = require( '@wordpress/dependency-extraction-we
 /**
  * Internal dependencies
  */
-const { normalizeJoin, stylesTransform, baseConfig, baseDir } = require( './shared' );
+const { baseDir, getBaseConfig, normalizeJoin, stylesTransform } = require( './shared' );
 const { dependencies } = require( '../../package' );
 
 const exportDefaultPackages = [
@@ -129,8 +128,9 @@ module.exports = function( env = { environment: 'production', watch: false, buil
 		to: normalizeJoin(baseDir, `src/${ phpFiles[ filename ] }` ),
 	} ) );
 
+	const baseConfig = getBaseConfig( env );
 	const config = {
-		...baseConfig( env ),
+		...baseConfig,
 		entry: packages.reduce( ( memo, packageName ) => {
 			memo[ packageName ] = {
 				import: normalizeJoin(baseDir, `node_modules/@wordpress/${ packageName }` ),
@@ -151,15 +151,7 @@ module.exports = function( env = { environment: 'production', watch: false, buil
 			path: normalizeJoin(baseDir, `${ buildTarget }/js/dist` ),
 		},
 		plugins: [
-			new DefinePlugin( {
-				// Inject the `IS_GUTENBERG_PLUGIN` global, used for feature flagging.
-				'process.env.IS_GUTENBERG_PLUGIN': false,
-				// Inject the `IS_WORDPRESS_CORE` global, used for feature flagging.
-				'process.env.IS_WORDPRESS_CORE': true,
-				'process.env.FORCE_REDUCED_MOTION': JSON.stringify(
-					process.env.FORCE_REDUCED_MOTION
-				),
-			} ),
+			...baseConfig.plugins,
 			new DependencyExtractionPlugin( {
 				injectPolyfill: true,
 				combineAssets: true,
diff --git a/tools/webpack/shared.js b/tools/webpack/shared.js
index f6930d5e6ef7f..5aea4204d31a2 100644
--- a/tools/webpack/shared.js
+++ b/tools/webpack/shared.js
@@ -1,13 +1,14 @@
 /**
  * External dependencies
  */
+const { DefinePlugin } = require( 'webpack' );
 const TerserPlugin = require( 'terser-webpack-plugin' );
 const postcss = require( 'postcss' );
 const { join } = require( 'path' );
 
 const baseDir = join( __dirname, '../../' );
 
-const baseConfig = ( env ) => {
+const getBaseConfig = ( env ) => {
 	const mode = env.environment;
 
 	const config = {
@@ -41,6 +42,16 @@ const baseConfig = ( env ) => {
 		},
 		stats: 'errors-only',
 		watch: env.watch,
+		plugins: [
+			new DefinePlugin( {
+				// Inject the `IS_GUTENBERG_PLUGIN` global, used for feature flagging.
+				'process.env.IS_GUTENBERG_PLUGIN': false,
+				// Inject the `IS_WORDPRESS_CORE` global, used for feature flagging.
+				'process.env.IS_WORDPRESS_CORE': true,
+				// Inject the `SCRIPT_DEBUG` global, used for dev versions of JavaScript.
+				SCRIPT_DEBUG: mode === 'development',
+			} ),
+		],
 	};
 
 	if ( mode === 'development' && env.buildTarget === 'build/' ) {
@@ -79,7 +90,7 @@ const normalizeJoin = ( ...paths ) => join( ...paths ).replace( /\\/g, '/' );
 
 module.exports = {
 	baseDir,
-	baseConfig,
+	getBaseConfig,
 	normalizeJoin,
 	stylesTransform,
 };