diff --git a/src/ProtectedEvaluator.ts b/src/ProtectedEvaluator.ts
index 0d6aaf1..efefabd 100644
--- a/src/ProtectedEvaluator.ts
+++ b/src/ProtectedEvaluator.ts
@@ -29,7 +29,7 @@ const Evaluator: IEvaluator = {
       return baseEvaluate(func, args, ...rest);
     }
 
-    func = `result = (function() {${func}})()`;
+    func = `result = (function() { value = ${func}; return value; })()`;
     const initFunc = function(interpreter, globalObject) {
       Object.keys(args).forEach((variable) => {
         // Exclude variables which have circular references
diff --git a/webpack.config.js b/webpack.config.js
index 87875e3..e9f9bcb 100644
--- a/webpack.config.js
+++ b/webpack.config.js
@@ -24,6 +24,6 @@ module.exports = {
     }
   },
   externals: {
-    formiojs: 'Formio',
+    '@formio/js': 'Formio',
   },
 };