diff --git a/gulpfile.js b/gulpfile.js
index b96010742c..0bd503e510 100644
--- a/gulpfile.js
+++ b/gulpfile.js
@@ -24,7 +24,7 @@ const size = require('gulp-size');
 const lazypipe = require('lazypipe');
 const closure = require('google-closure-compiler').gulp();
 const minimalDocument = require('./util/minimalDocument.js');
-const dom5 = require('dom5');
+const dom5 = require('dom5/lib/index-next');
 const parse5 = require('parse5');
 const replace = require('gulp-replace');
 
diff --git a/package-lock.json b/package-lock.json
index a8d8014ef2..7229a16e00 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -2735,24 +2735,14 @@
       }
     },
     "dom5": {
-      "version": "2.3.0",
-      "resolved": "https://registry.npmjs.org/dom5/-/dom5-2.3.0.tgz",
-      "integrity": "sha1-+CBJdb0NrLvltYqKk//B/tD/zSo=",
+      "version": "3.0.0",
+      "resolved": "https://registry.npmjs.org/dom5/-/dom5-3.0.0.tgz",
+      "integrity": "sha512-PbE+7C4Sh1dHDTLNuSDaMUGD1ivDiSZw0L+a9xVUzUKeQ8w3vdzfKHRA07CxcrFZZOa1SGl2nIJ9T49j63q+bg==",
       "dev": true,
       "requires": {
-        "@types/clone": "0.1.30",
-        "@types/node": "6.0.96",
         "@types/parse5": "2.2.34",
         "clone": "2.1.1",
-        "parse5": "2.2.3"
-      },
-      "dependencies": {
-        "parse5": {
-          "version": "2.2.3",
-          "resolved": "https://registry.npmjs.org/parse5/-/parse5-2.2.3.tgz",
-          "integrity": "sha1-DE/EHBAAxea5PUiwP4CDg3g06fY=",
-          "dev": true
-        }
+        "parse5": "4.0.0"
       }
     },
     "domelementtype": {
@@ -6670,13 +6660,10 @@
       "dev": true
     },
     "parse5": {
-      "version": "3.0.3",
-      "resolved": "https://registry.npmjs.org/parse5/-/parse5-3.0.3.tgz",
-      "integrity": "sha512-rgO9Zg5LLLkfJF9E6CCmXlSE4UVceloys8JrFqCcHloC3usd/kJCyPDwH2SOlzix2j3xaP9sUX3e8+kvkuleAA==",
-      "dev": true,
-      "requires": {
-        "@types/node": "6.0.96"
-      }
+      "version": "4.0.0",
+      "resolved": "https://registry.npmjs.org/parse5/-/parse5-4.0.0.tgz",
+      "integrity": "sha512-VrZ7eOd3T1Fk4XWNXMgiGBK/z0MG48BWG2uQNU4I72fkQuKUTZpl+u9k+CxEG0twMVzSmXEEz12z5Fnw1jIQFA==",
+      "dev": true
     },
     "parseqs": {
       "version": "0.0.5",
@@ -6951,6 +6938,19 @@
         "strip-indent": "2.0.0"
       },
       "dependencies": {
+        "dom5": {
+          "version": "2.3.0",
+          "resolved": "https://registry.npmjs.org/dom5/-/dom5-2.3.0.tgz",
+          "integrity": "sha1-+CBJdb0NrLvltYqKk//B/tD/zSo=",
+          "dev": true,
+          "requires": {
+            "@types/clone": "0.1.30",
+            "@types/node": "6.0.96",
+            "@types/parse5": "2.2.34",
+            "clone": "2.1.1",
+            "parse5": "2.2.3"
+          }
+        },
         "parse5": {
           "version": "2.2.3",
           "resolved": "https://registry.npmjs.org/parse5/-/parse5-2.2.3.tgz",
@@ -7021,6 +7021,27 @@
           "integrity": "sha1-uI+UqCzzi4eR1YBG6kAprYjKmdE=",
           "dev": true
         },
+        "dom5": {
+          "version": "2.3.0",
+          "resolved": "https://registry.npmjs.org/dom5/-/dom5-2.3.0.tgz",
+          "integrity": "sha1-+CBJdb0NrLvltYqKk//B/tD/zSo=",
+          "dev": true,
+          "requires": {
+            "@types/clone": "0.1.30",
+            "@types/node": "6.0.96",
+            "@types/parse5": "2.2.34",
+            "clone": "2.1.1",
+            "parse5": "2.2.3"
+          },
+          "dependencies": {
+            "clone": {
+              "version": "2.1.1",
+              "resolved": "https://registry.npmjs.org/clone/-/clone-2.1.1.tgz",
+              "integrity": "sha1-0hfR6WERjjrJpLi7oyhVU79kfNs=",
+              "dev": true
+            }
+          }
+        },
         "duplexer2": {
           "version": "0.1.4",
           "resolved": "https://registry.npmjs.org/duplexer2/-/duplexer2-0.1.4.tgz",
@@ -7313,6 +7334,19 @@
           "integrity": "sha1-SLaZwn4zS/ifEIkr5DL25MfTSn8=",
           "dev": true
         },
+        "dom5": {
+          "version": "2.3.0",
+          "resolved": "https://registry.npmjs.org/dom5/-/dom5-2.3.0.tgz",
+          "integrity": "sha1-+CBJdb0NrLvltYqKk//B/tD/zSo=",
+          "dev": true,
+          "requires": {
+            "@types/clone": "0.1.30",
+            "@types/node": "6.0.96",
+            "@types/parse5": "2.2.34",
+            "clone": "2.1.1",
+            "parse5": "2.2.3"
+          }
+        },
         "parse5": {
           "version": "2.2.3",
           "resolved": "https://registry.npmjs.org/parse5/-/parse5-2.2.3.tgz",
@@ -7506,6 +7540,27 @@
           "integrity": "sha1-SLaZwn4zS/ifEIkr5DL25MfTSn8=",
           "dev": true
         },
+        "dom5": {
+          "version": "2.3.0",
+          "resolved": "https://registry.npmjs.org/dom5/-/dom5-2.3.0.tgz",
+          "integrity": "sha1-+CBJdb0NrLvltYqKk//B/tD/zSo=",
+          "dev": true,
+          "requires": {
+            "@types/clone": "0.1.30",
+            "@types/node": "6.0.101",
+            "@types/parse5": "2.2.34",
+            "clone": "2.1.1",
+            "parse5": "2.2.3"
+          },
+          "dependencies": {
+            "@types/node": {
+              "version": "6.0.101",
+              "resolved": "https://registry.npmjs.org/@types/node/-/node-6.0.101.tgz",
+              "integrity": "sha512-IQ7V3D6+kK1DArTqTBrnl3M+YgJZLw8ta8w3Q9xjR79HaJzMAoTbZ8TNzUTztrkCKPTqIstE2exdbs1FzsYLUw==",
+              "dev": true
+            }
+          }
+        },
         "etag": {
           "version": "1.7.0",
           "resolved": "https://registry.npmjs.org/etag/-/etag-1.7.0.tgz",
diff --git a/package.json b/package.json
index 3d315d6da3..ab8afc8f34 100644
--- a/package.json
+++ b/package.json
@@ -14,7 +14,7 @@
     "@webcomponents/webcomponentsjs": "^1.1.0",
     "babel-preset-minify": "^0.2.0",
     "del": "^3.0.0",
-    "dom5": "^2.3.0",
+    "dom5": "^3.0.0",
     "eslint-plugin-html": "^4.0.1",
     "fs-extra": "^4.0.3",
     "google-closure-compiler": "^20171112.0.0",
@@ -27,7 +27,7 @@
     "gulp-vulcanize": "^6.0.1",
     "lazypipe": "^1.0.1",
     "merge-stream": "^1.0.1",
-    "parse5": "^3.0.3",
+    "parse5": "^4.0.0",
     "polymer-build": "^2.1.1",
     "run-sequence": "^2.2.0",
     "through2": "^2.0.0",