diff --git a/.make-packages.js b/.make-packages.js
index d21ac516ec..848f2c4def 100644
--- a/.make-packages.js
+++ b/.make-packages.js
@@ -53,14 +53,14 @@ let rootPackageJson = Object.assign({}, pkg, {
 // functionality requires that the most broad mapping (rxjs/operators) be at
 // the end of the alias mapping object. Created Webpack issue:
 // https://github.com/webpack/webpack/issues/5870
-const fileNames = klawSync(LEGACY_REEXPORT_ROOT, {
+const fileNames = klawSync(ESM5_ROOT, {
   nodir: true,
   filter: function(item) {
     return item.path.endsWith('.js');
   }
 })
 .map(item => item.path)
-.map(path => path.slice((`${__dirname}/${LEGACY_REEXPORT_ROOT}`).length))
+.map(path => path.slice((`${__dirname}/${ESM5_ROOT}`).length))
 .sort().reverse();
 
 // Execute build optimizer transforms on ESM5 files
diff --git a/package.json b/package.json
index 6ff2847dc9..8cdf67a618 100644
--- a/package.json
+++ b/package.json
@@ -189,7 +189,7 @@
     "tslib": "^1.9.0"
   },
   "devDependencies": {
-    "@angular-devkit/build-optimizer": "0.0.24",
+    "@angular-devkit/build-optimizer": "0.4.6",
     "@types/chai": "4.1.2",
     "@types/lodash": "4.14.102",
     "@types/mocha": "2.2.48",