diff --git a/package-lock.json b/package-lock.json
index 95e652b..6495aee 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -111,6 +111,45 @@
         "to-fast-properties": "^2.0.0"
       }
     },
+    "@types/create-hash": {
+      "version": "1.2.0",
+      "resolved": "https://registry.npmjs.org/@types/create-hash/-/create-hash-1.2.0.tgz",
+      "integrity": "sha512-tvo2dQ4TRKi0GYsblpWnhpJKR7Dvyyu+JdWhu4K5J8MKKONQfD9imAI/RIZn9brZXJ7n5DHxjwMpB4XOIVvGaw==",
+      "dev": true,
+      "requires": {
+        "@types/node": "*"
+      }
+    },
+    "@types/node": {
+      "version": "11.11.6",
+      "resolved": "https://registry.npmjs.org/@types/node/-/node-11.11.6.tgz",
+      "integrity": "sha512-Exw4yUWMBXM3X+8oqzJNRqZSwUAaS4+7NdvHqQuFi/d+synz++xmX3QIf+BFqneW8N31R8Ky+sikfZUXq07ggQ==",
+      "dev": true
+    },
+    "@types/pbkdf2": {
+      "version": "3.0.0",
+      "resolved": "https://registry.npmjs.org/@types/pbkdf2/-/pbkdf2-3.0.0.tgz",
+      "integrity": "sha512-6J6MHaAlBJC/eVMy9jOwj9oHaprfutukfW/Dyt0NEnpQ/6HN6YQrpvLwzWdWDeWZIdenjGHlbYDzyEODO5Z+2Q==",
+      "dev": true,
+      "requires": {
+        "@types/node": "*"
+      }
+    },
+    "@types/randombytes": {
+      "version": "2.0.0",
+      "resolved": "https://registry.npmjs.org/@types/randombytes/-/randombytes-2.0.0.tgz",
+      "integrity": "sha512-bz8PhAVlwN72vqefzxa14DKNT8jK/mV66CSjwdVQM/k3Th3EPKfUtdMniwZgMedQTFuywAsfjnZsg+pEnltaMA==",
+      "dev": true,
+      "requires": {
+        "@types/node": "*"
+      }
+    },
+    "@types/unorm": {
+      "version": "1.3.27",
+      "resolved": "https://registry.npmjs.org/@types/unorm/-/unorm-1.3.27.tgz",
+      "integrity": "sha1-YL2zuy5cnr5tCC3zoTypkjAsyno=",
+      "dev": true
+    },
     "acorn": {
       "version": "5.7.3",
       "resolved": "https://registry.npmjs.org/acorn/-/acorn-5.7.3.tgz",
diff --git a/package.json b/package.json
index b7abb88..869120c 100644
--- a/package.json
+++ b/package.json
@@ -34,6 +34,10 @@
     "unorm": "^1.3.3"
   },
   "devDependencies": {
+    "@types/create-hash": "^1.2.0",
+    "@types/pbkdf2": "^3.0.0",
+    "@types/randombytes": "^2.0.0",
+    "@types/unorm": "^1.3.27",
     "node-fetch": "^1.6.3",
     "nyc": "^13.1.0",
     "prettier": "^1.16.4",