diff --git a/package-lock.json b/package-lock.json
index 59f673b..b866688 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1599,6 +1599,11 @@
         "moment-timezone": "^0.5.17"
       }
     },
+    "ipaddr.js": {
+      "version": "1.8.1",
+      "resolved": "https://registry.npmjs.org/ipaddr.js/-/ipaddr.js-1.8.1.tgz",
+      "integrity": "sha1-+kt5+kf9Pe9eOxWYJRYcClGclCc="
+    },
     "is-buffer": {
       "version": "1.1.6",
       "resolved": "https://registry.npmjs.org/is-buffer/-/is-buffer-1.1.6.tgz",
diff --git a/package.json b/package.json
index 5444dff..8e75e0d 100644
--- a/package.json
+++ b/package.json
@@ -22,6 +22,7 @@
     "hbs": "~4.0.1",
     "http-errors": "~1.6.2",
     "ical-generator": "^1.0.4",
+    "ipaddr.js": "^1.8.1",
     "less-middleware": "~3.0.1",
     "markdown-it": "^8.4.2",
     "mkdirp": "^0.5.1",