diff --git a/webpack.config.js b/webpack.config.js
index 877f023..fac3947 100644
--- a/webpack.config.js
+++ b/webpack.config.js
@@ -8,6 +8,8 @@ if (!Encore.isRuntimeEnvironmentConfigured()) {
     Encore.configureRuntimeEnvironment(process.env.NODE_ENV || 'dev');
 }
 
+const TERSER_PARALLEL = process.env.hasOwnProperty('CPU_COUNT') ? parseInt(process.env.CPU_COUNT) : true;
+
 Encore
     // directory where compiled assets will be stored
     .setOutputPath('public/build/')
@@ -52,7 +54,7 @@ Encore
     })
 
     .configureTerserPlugin((config) => {
-      config.parallel = process.env.CPU_COUNT || true;
+      config.parallel = TERSER_PARALLEL;
     })
 
     // enables @babel/preset-env polyfills