diff --git a/lighthouse-core/gather/gatherers/dobetterweb/optimized-images.js b/lighthouse-core/gather/gatherers/dobetterweb/optimized-images.js
index 7dee469fe2a9..8279f8ee188a 100644
--- a/lighthouse-core/gather/gatherers/dobetterweb/optimized-images.js
+++ b/lighthouse-core/gather/gatherers/dobetterweb/optimized-images.js
@@ -185,8 +185,7 @@ class OptimizedImages extends Gatherer {
         }
 
         /** @type {LH.Artifacts.OptimizedImage} */
-        // @ts-ignore TODO(bckenny): fix browserify/Object.spread. See https://github.com/GoogleChrome/lighthouse/issues/5152
-        const image = Object.assign({failed: false}, stats, record);
+        const image = {failed: false, ...stats, ...record};
         results.push(image);
       } catch (err) {
         // Track this with Sentry since these errors aren't surfaced anywhere else, but we don't
@@ -199,8 +198,7 @@ class OptimizedImages extends Gatherer {
         });
 
         /** @type {LH.Artifacts.OptimizedImageError} */
-        // @ts-ignore TODO(bckenny): see above browserify/Object.spread TODO.
-        const imageError = Object.assign({failed: true, errMsg: err.message}, record);
+        const imageError = {failed: true, errMsg: err.message, ...record};
         results.push(imageError);
       }
     }
diff --git a/lighthouse-extension/gulpfile.js b/lighthouse-extension/gulpfile.js
index 7cb8fb040104..6a7b7f172145 100644
--- a/lighthouse-extension/gulpfile.js
+++ b/lighthouse-extension/gulpfile.js
@@ -1,6 +1,20 @@
 // generated on 2016-03-19 using generator-chrome-extension 0.5.4
 
 'use strict';
+
+const fs = require('fs');
+// HACK: patch astw before it's required to use acorn with ES2018
+// We add the right acorn version to package.json deps, resolve the path to it here,
+// and then inject the modified require statement into astw's code.
+// see https://github.com/GoogleChrome/lighthouse/issues/5152
+const acornPath = require.resolve('acorn');
+const astwPath = require.resolve('astw/index.js');
+const astwOriginalContent = fs.readFileSync(astwPath, 'utf8');
+const astwPatchedContent = astwOriginalContent
+  .replace('ecmaVersion: opts.ecmaVersion || 8', 'ecmaVersion: 2018')
+  .replace(`require('acorn')`, `require(${JSON.stringify(acornPath)})`);
+fs.writeFileSync(astwPath, astwPatchedContent);
+
 const del = require('del');
 const gutil = require('gulp-util');
 const runSequence = require('run-sequence');
diff --git a/lighthouse-extension/package.json b/lighthouse-extension/package.json
index 5570561d74a8..bb2d726a5943 100644
--- a/lighthouse-extension/package.json
+++ b/lighthouse-extension/package.json
@@ -7,9 +7,11 @@
   "scripts": {
     "watch": "gulp watch",
     "build": "gulp build:production",
+    "debug-build": "node --inspect-brk ./node_modules/.bin/gulp build:production",
     "test": "mocha test/**/*-test.js"
   },
   "devDependencies": {
+    "acorn": "^5.5.3",
     "babel-plugin-syntax-object-rest-spread": "^6.13.0",
     "brfs": "^1.6.1",
     "browserify": "^16.2.0",
@@ -28,7 +30,8 @@
     "through2": "^2.0.1"
   },
   "resolutions": {
-    "browserify/insert-module-globals/lexical-scope/astw": "2.2.0"
+    "browserify/insert-module-globals/lexical-scope/astw": "2.2.0",
+    "**/astw/acorn": "5.5.3"
   },
   "dependencies": {}
 }
diff --git a/lighthouse-extension/yarn.lock b/lighthouse-extension/yarn.lock
index a56e78be224e..87b249957342 100644
--- a/lighthouse-extension/yarn.lock
+++ b/lighthouse-extension/yarn.lock
@@ -22,18 +22,14 @@ acorn-node@^1.2.0, acorn-node@^1.3.0:
     acorn "^5.4.1"
     xtend "^4.0.1"
 
+acorn@5.5.3, acorn@^4.0.3, acorn@^5.0.0, acorn@^5.4.1, acorn@^5.5.3:
+  version "5.5.3"
+  resolved "https://registry.yarnpkg.com/acorn/-/acorn-5.5.3.tgz#f473dd47e0277a08e28e9bec5aeeb04751f0b8c9"
+
 acorn@^3.0.4:
   version "3.3.0"
   resolved "https://registry.yarnpkg.com/acorn/-/acorn-3.3.0.tgz#45e37fb39e8da3f25baee3ff5369e2bb5f22017a"
 
-acorn@^4.0.3:
-  version "4.0.13"
-  resolved "https://registry.yarnpkg.com/acorn/-/acorn-4.0.13.tgz#105495ae5361d697bd195c825192e1ad7f253787"
-
-acorn@^5.0.0, acorn@^5.4.1:
-  version "5.5.3"
-  resolved "https://registry.yarnpkg.com/acorn/-/acorn-5.5.3.tgz#f473dd47e0277a08e28e9bec5aeeb04751f0b8c9"
-
 acorn@^5.1.1:
   version "5.1.2"
   resolved "https://registry.yarnpkg.com/acorn/-/acorn-5.1.2.tgz#911cb53e036807cf0fa778dc5d370fbd864246d7"