diff --git a/.eslintrc.json b/.eslintrc.json
index 94a41a6411..cc13518ec5 100644
--- a/.eslintrc.json
+++ b/.eslintrc.json
@@ -10,8 +10,9 @@
     "html"
   ],
   "globals": {
-    "CustomElements": true,
-    "HTMLImports": true,
-    "Polymer": true
+    "CustomElements": false,
+    "HTMLImports": false,
+    "Polymer": false,
+    "WeakMap": false
   }
 }
diff --git a/gulpfile.js b/gulpfile.js
index a3cf4e6881..afeed0bd7e 100644
--- a/gulpfile.js
+++ b/gulpfile.js
@@ -68,8 +68,8 @@ gulp.task('micro', vulcanizeWithExcludes(micro));
 gulp.task('mini', vulcanizeWithExcludes(mini, [micro]));
 gulp.task('max', vulcanizeWithExcludes(max, [mini, micro]));
 
-gulp.task('clean', function(cb) {
-  del(workdir, cb);
+gulp.task('clean', function() {
+  return del(workdir);
 });
 
 // copy bower.json into dist folder
@@ -99,8 +99,8 @@ gulp.task('restore-src', function() {
     .pipe(gulp.dest('.'));
 });
 
-gulp.task('cleanup-switch', function(cb) {
-  del([mini + '.bak', micro + '.bak', max + '.bak'], cb);
+gulp.task('cleanup-switch', function() {
+  return del([mini + '.bak', micro + '.bak', max + '.bak']);
 });
 
 gulp.task('switch-build', function() {
diff --git a/package.json b/package.json
index 58036b0e19..764ce44983 100644
--- a/package.json
+++ b/package.json
@@ -8,15 +8,15 @@
     "test": "test"
   },
   "devDependencies": {
-    "del": "^1.1.1",
+    "del": "^2.2.0",
     "eslint-plugin-html": "^1.3.0",
     "gulp": "^3.8.11",
     "gulp-audit": "^1.0.0",
-    "gulp-eslint": "^1.1.1",
+    "gulp-eslint": "^2.0.0",
     "gulp-rename": "^1.2.2",
     "gulp-replace": "^0.5.3",
     "gulp-vulcanize": "^6.0.1",
-    "lazypipe": "^0.2.3",
+    "lazypipe": "^1.0.1",
     "polyclean": "^1.2.0",
     "run-sequence": "^1.1.0",
     "web-component-tester": "^4"