diff --git a/packages/marko-web/express/index.js b/packages/marko-web/express/index.js
index 13422149a..1f09c19bb 100644
--- a/packages/marko-web/express/index.js
+++ b/packages/marko-web/express/index.js
@@ -50,6 +50,9 @@ module.exports = (config = {}) => {
     }));
   }
 
+  // Set the tenant key to the app.
+  app.locals.tenantKey = tenantKey;
+
   // Set the core config.
   app.locals.config = new CoreConfig({ ...config.coreConfig, distDir });