diff --git a/package-lock.json b/package-lock.json
index 0a91c0f..a39a6fd 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1277,6 +1277,7 @@
           "version": "0.1.4",
           "bundled": true,
           "dev": true,
+          "optional": true,
           "requires": {
             "kind-of": "^3.0.2",
             "longest": "^1.0.1",
@@ -1598,7 +1599,8 @@
         "is-buffer": {
           "version": "1.1.6",
           "bundled": true,
-          "dev": true
+          "dev": true,
+          "optional": true
         },
         "is-builtin-module": {
           "version": "1.0.0",
@@ -1682,6 +1684,7 @@
           "version": "3.2.2",
           "bundled": true,
           "dev": true,
+          "optional": true,
           "requires": {
             "is-buffer": "^1.1.5"
           }
@@ -1728,7 +1731,8 @@
         "longest": {
           "version": "1.0.1",
           "bundled": true,
-          "dev": true
+          "dev": true,
+          "optional": true
         },
         "lru-cache": {
           "version": "4.1.3",
@@ -1994,7 +1998,8 @@
         "repeat-string": {
           "version": "1.6.1",
           "bundled": true,
-          "dev": true
+          "dev": true,
+          "optional": true
         },
         "require-directory": {
           "version": "2.1.1",
@@ -2655,14 +2660,15 @@
       }
     },
     "rollup-plugin-uglify": {
-      "version": "5.0.2",
-      "resolved": "https://registry.npmjs.org/rollup-plugin-uglify/-/rollup-plugin-uglify-5.0.2.tgz",
-      "integrity": "sha512-CRRyMgKjTwTx1GXnn+v1VYV+6De5NyPB1UBStsQIQ+asrxvP7dK43cg2pf1vyFNr/NIHGvfYAR9Yo4j+5ZMQsw==",
+      "version": "6.0.0",
+      "resolved": "https://registry.npmjs.org/rollup-plugin-uglify/-/rollup-plugin-uglify-6.0.0.tgz",
+      "integrity": "sha512-XtzZd159QuOaXNvcxyBcbUCSoBsv5YYWK+7ZwUyujSmISst8avRfjWlp7cGu8T2O52OJnpEBvl+D4WLV1k1iQQ==",
       "dev": true,
       "requires": {
         "@babel/code-frame": "^7.0.0",
         "jest-worker": "^23.2.0",
-        "uglify-js": "^3.4.8"
+        "serialize-javascript": "^1.5.0",
+        "uglify-js": "^3.4.9"
       },
       "dependencies": {
         "@babel/code-frame": {
@@ -2711,6 +2717,12 @@
       "integrity": "sha512-PqpAxfrEhlSUWge8dwIp4tZnQ25DIOthpiaHNIthsjEFQD6EvqUKUDM7L8O2rShkFccYo1VjJR0coWfNkCubRw==",
       "dev": true
     },
+    "serialize-javascript": {
+      "version": "1.5.0",
+      "resolved": "https://registry.npmjs.org/serialize-javascript/-/serialize-javascript-1.5.0.tgz",
+      "integrity": "sha512-Ga8c8NjAAp46Br4+0oZ2WxJCwIzwP60Gq1YPgU+39PiTVxyed/iKE/zyZI6+UlVYH5Q4PaQdHhcegIFPZTUfoQ==",
+      "dev": true
+    },
     "set-blocking": {
       "version": "2.0.0",
       "resolved": "https://registry.npmjs.org/set-blocking/-/set-blocking-2.0.0.tgz",
diff --git a/package.json b/package.json
index 2216787..161fda4 100644
--- a/package.json
+++ b/package.json
@@ -57,7 +57,7 @@
     "nyc": "^13.0.1",
     "rimraf": "^2.6.2",
     "rollup": "^0.65.2",
-    "rollup-plugin-uglify": "^5.0.2",
+    "rollup-plugin-uglify": "^6.0.0",
     "ts-node": "^7.0.1",
     "tslint": "^5.11.0",
     "typedoc": "^0.12.0",