diff --git a/package-lock.json b/package-lock.json
index f6470452..cd6b5eb0 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -90,6 +90,7 @@
       "version": "5.5.2",
       "resolved": "https://registry.npmjs.org/ajv/-/ajv-5.5.2.tgz",
       "integrity": "sha1-c7Xuyj+rZT49P5Qis0GtQiBdyWU=",
+      "dev": true,
       "requires": {
         "co": "4.6.0",
         "fast-deep-equal": "1.0.0",
@@ -100,7 +101,8 @@
     "ajv-keywords": {
       "version": "2.1.1",
       "resolved": "https://registry.npmjs.org/ajv-keywords/-/ajv-keywords-2.1.1.tgz",
-      "integrity": "sha1-YXmX/F9gV2iUxDX5QNgZ4TW4B2I="
+      "integrity": "sha1-YXmX/F9gV2iUxDX5QNgZ4TW4B2I=",
+      "dev": true
     },
     "align-text": {
       "version": "0.1.4",
@@ -1633,7 +1635,8 @@
     "co": {
       "version": "4.6.0",
       "resolved": "https://registry.npmjs.org/co/-/co-4.6.0.tgz",
-      "integrity": "sha1-bqa989hTrlTMuOR7+gvz+QMfsYQ="
+      "integrity": "sha1-bqa989hTrlTMuOR7+gvz+QMfsYQ=",
+      "dev": true
     },
     "code-point-at": {
       "version": "1.1.0",
@@ -7895,12 +7898,29 @@
       "dev": true
     },
     "schema-utils": {
-      "version": "0.4.3",
-      "resolved": "https://registry.npmjs.org/schema-utils/-/schema-utils-0.4.3.tgz",
-      "integrity": "sha512-sgv/iF/T4/SewJkaVpldKC4WjSkz0JsOh2eKtxCPpCO1oR05+7MOF+H476HVRbLArkgA7j5TRJJ4p2jdFkUGQQ==",
+      "version": "0.4.5",
+      "resolved": "https://registry.npmjs.org/schema-utils/-/schema-utils-0.4.5.tgz",
+      "integrity": "sha512-yYrjb9TX2k/J1Y5UNy3KYdZq10xhYcF8nMpAW6o3hy6Q8WSIEf9lJHG/ePnOBfziPM3fvQwfOwa13U/Fh8qTfA==",
       "requires": {
-        "ajv": "5.5.2",
-        "ajv-keywords": "2.1.1"
+        "ajv": "6.2.1",
+        "ajv-keywords": "3.1.0"
+      },
+      "dependencies": {
+        "ajv": {
+          "version": "6.2.1",
+          "resolved": "https://registry.npmjs.org/ajv/-/ajv-6.2.1.tgz",
+          "integrity": "sha1-KKarxJOiq+D7TIUHrK7bQ/pVBnE=",
+          "requires": {
+            "fast-deep-equal": "1.0.0",
+            "fast-json-stable-stringify": "2.0.0",
+            "json-schema-traverse": "0.3.1"
+          }
+        },
+        "ajv-keywords": {
+          "version": "3.1.0",
+          "resolved": "https://registry.npmjs.org/ajv-keywords/-/ajv-keywords-3.1.0.tgz",
+          "integrity": "sha1-rCsnk5xUPpXSwG5/f1wnvkqlQ74="
+        }
       }
     },
     "semver": {
diff --git a/package.json b/package.json
index cf321828..67a4a4f9 100644
--- a/package.json
+++ b/package.json
@@ -34,7 +34,7 @@
     "cacache": "^10.0.1",
     "find-cache-dir": "^1.0.0",
     "serialize-javascript": "^1.4.0",
-    "schema-utils": "^0.4.2",
+    "schema-utils": "^0.4.5",
     "source-map": "^0.6.1",
     "uglify-es": "^3.3.4",
     "webpack-sources": "^1.1.0",
diff --git a/test/__snapshots__/invalid-options.test.js.snap b/test/__snapshots__/invalid-options.test.js.snap
index d6889a99..2dfff786 100644
--- a/test/__snapshots__/invalid-options.test.js.snap
+++ b/test/__snapshots__/invalid-options.test.js.snap
@@ -187,7 +187,7 @@ exports[`warnings 1`] = `Array []`;
 exports[`when applied with invalid options throws validation errors 1`] = `
 "UglifyJs Plugin Invalid Options
 
-options['doesntExist'] should NOT have additional properties
+options['doesntExist'] is an invalid additional property
 "
 `;