diff --git a/assets/js/src/welcome_wizard/steps_controller.jsx b/assets/js/src/welcome_wizard/steps_controller.jsx
index 1527c3ea38..0aec308e0b 100644
--- a/assets/js/src/welcome_wizard/steps_controller.jsx
+++ b/assets/js/src/welcome_wizard/steps_controller.jsx
@@ -82,7 +82,7 @@ const WelcomeWizardStepsController = (props) => {
       </div>
       <div className="mailpoet_welcome_wizard_flex">
         <div className="mailpoet_welcome_wizard_illustration">
-          <img src={window['step_' + step + '_illustration_url']} alt="" />
+          <img src={window[`step_${step}_illustration_url`]} alt="" />
         </div>
         <div className="mailpoet_welcome_wizard_step">
           { step <= stepsCount