diff --git a/src/scripts/build.ts b/src/scripts/build.ts
index 518b19fbf..4fb53bebb 100644
--- a/src/scripts/build.ts
+++ b/src/scripts/build.ts
@@ -6,7 +6,11 @@ export default function build(
 	config: Rsg.SanitizedStyleguidistConfig,
 	callback: (err: Error, stats: webpack.Stats) => void
 ) {
-	return webpack(makeWebpackConfig(config, 'production'), (err, stats) => {
+	// FIX: Allow process.env.NODE_ENV to override the default 'production' state
+	// This prevents the mismatch where Babel thinks it is in one env and Styleguidist another.
+	const env = (process.env.NODE_ENV as 'development' | 'production' | 'none') || 'production';
+
+	return webpack(makeWebpackConfig(config, env), (err, stats) => {
 		// require('fs').writeFileSync('stats.json', JSON.stringify(stats.toJson()));
 		callback(err as Error, stats as webpack.Stats);
 	});
diff --git a/src/scripts/make-webpack-config.ts b/src/scripts/make-webpack-config.ts
index 9665df9a3..7b6a159ef 100644
--- a/src/scripts/make-webpack-config.ts
+++ b/src/scripts/make-webpack-config.ts
@@ -26,9 +26,13 @@ export default function (
 	config: Rsg.SanitizedStyleguidistConfig,
 	env: 'development' | 'production' | 'none'
 ): Configuration {
-	process.env.NODE_ENV = process.env.NODE_ENV || env;
+	// FIX: Prioritize the existing process.env.NODE_ENV if it's already set
+	// This ensures that Babel and other loaders see the same environment as Styleguidist
+	const activeEnv = process.env.NODE_ENV || env;
+	process.env.NODE_ENV = activeEnv;
 
-	const isProd = env === 'production';
+	// Use the resolved activeEnv for production checks
+	const isProd = activeEnv === 'production';
 
 	const template = isFunction(config.template) ? config.template : MiniHtmlWebpackTemplate;
 	const templateContext = isFunction(config.template) ? {} : config.template;
@@ -44,7 +48,8 @@ export default function (
 
 	let webpackConfig: Configuration = {
 		entry: config.require.concat([path.resolve(sourceDir, 'index')]),
-		mode: env,
+		// FIX: Use activeEnv for mode to keep Webpack optimization in sync with NODE_ENV
+		mode: activeEnv as 'development' | 'production' | 'none',
 		output: {
 			path: config.styleguideDir,
 			filename: 'build/[name].bundle.js',