diff --git a/broccoli/to-es5.js b/broccoli/to-es5.js
index d921da76abe..be04f6e7e3e 100644
--- a/broccoli/to-es5.js
+++ b/broccoli/to-es5.js
@@ -43,7 +43,7 @@ module.exports = function toES5(tree, _options) {
     ['transform-es2015-parameters'],
     ['transform-es2015-computed-properties', {loose: true}],
     ['transform-es2015-shorthand-properties'],
-    ['transform-es2015-block-scoping'],
+    ['transform-es2015-block-scoping', { 'throwIfClosureRequired': true }],
     ['check-es2015-constants'],
     ['transform-es2015-classes', { loose: true }],
     ['transform-proto-to-assign'],