diff --git a/package-lock.json b/package-lock.json
index 9037bcf..60b8b13 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -34,9 +34,9 @@
       }
     },
     "@openzeppelin/contracts": {
-      "version": "2.4.0",
-      "resolved": "https://registry.npmjs.org/@openzeppelin/contracts/-/contracts-2.4.0.tgz",
-      "integrity": "sha512-xeKP59REgow5TPBJh3S9BRIm7DDG+Rz3Nt4ANWGUkjk4305DHpyUD5CyMJ6nd2JMmZuFyx4mjvvlCtSJLRnN6w=="
+      "version": "4.4.2",
+      "resolved": "https://registry.npmjs.org/@openzeppelin/contracts/-/contracts-4.4.2.tgz",
+      "integrity": "sha512-NyJV7sJgoGYqbtNUWgzzOGW4T6rR19FmX1IJgXGdapGPWsuMelGJn9h03nos0iqfforCbCB0iYIR0MtIuIFLLw=="
     },
     "@sindresorhus/is": {
       "version": "0.14.0",
@@ -1237,23 +1237,6 @@
       "integrity": "sha1-l4hXRCxEdJ5CBmE+N5RiBYJqvYA=",
       "dev": true
     },
-    "detective": {
-      "version": "git://github.com/shtylman/node-detective.git#06d5cb4534818860b5a7f8d0a321dc7ae86d8e74",
-      "from": "git://github.com/shtylman/node-detective.git#06d5cb",
-      "dev": true,
-      "requires": {
-        "escodegen": "0.0.15",
-        "esprima": "1.0.2"
-      },
-      "dependencies": {
-        "esprima": {
-          "version": "1.0.2",
-          "resolved": "https://registry.npmjs.org/esprima/-/esprima-1.0.2.tgz",
-          "integrity": "sha1-gDm/nOrE2dLBX2IyZPspK1UCzq8=",
-          "dev": true
-        }
-      }
-    },
     "diffie-hellman": {
       "version": "5.0.3",
       "resolved": "https://registry.npmjs.org/diffie-hellman/-/diffie-hellman-5.0.3.tgz",
@@ -5232,6 +5215,23 @@
       "dev": true,
       "requires": {
         "detective": "git://github.com/shtylman/node-detective.git#06d5cb4534818860b5a7f8d0a321dc7ae86d8e74"
+      },
+      "dependencies": {
+        "detective": {
+          "version": "git://github.com/shtylman/node-detective.git#06d5cb4534818860b5a7f8d0a321dc7ae86d8e74",
+          "from": "git://github.com/shtylman/node-detective.git#06d5cb",
+          "dev": true,
+          "requires": {
+            "escodegen": "0.0.15",
+            "esprima": "1.0.2"
+          }
+        },
+        "esprima": {
+          "version": "1.0.2",
+          "resolved": "https://registry.npmjs.org/esprima/-/esprima-1.0.2.tgz",
+          "integrity": "sha1-gDm/nOrE2dLBX2IyZPspK1UCzq8=",
+          "dev": true
+        }
       }
     },
     "requireg": {
@@ -6830,6 +6830,35 @@
         "underscore": "1.9.1",
         "web3-core-helpers": "1.2.1",
         "websocket": "github:web3-js/WebSocket-Node#905deb4812572b344f5801f8c9ce8bb02799d82e"
+      },
+      "dependencies": {
+        "debug": {
+          "version": "2.6.9",
+          "resolved": "https://registry.npmjs.org/debug/-/debug-2.6.9.tgz",
+          "integrity": "sha512-bC7ElrdJaJnPbAP+1EotYvqZsb3ecl5wi6Bfi6BJTUcNowp6cvspg0jXznRTKDjm/E7AdgFBVeAPVMNcKGsHMA==",
+          "dev": true,
+          "requires": {
+            "ms": "2.0.0"
+          }
+        },
+        "nan": {
+          "version": "2.15.0",
+          "resolved": "https://registry.npmjs.org/nan/-/nan-2.15.0.tgz",
+          "integrity": "sha512-8ZtvEnA2c5aYCZYd1cvgdnU6cqwixRoYg70xPLWUws5ORTa/lnw+u4amixRS/Ac5U5mQVgp9pnlSUnbNWFaWZQ==",
+          "dev": true
+        },
+        "websocket": {
+          "version": "github:web3-js/WebSocket-Node#905deb4812572b344f5801f8c9ce8bb02799d82e",
+          "from": "github:web3-js/WebSocket-Node#polyfill/globalThis",
+          "dev": true,
+          "requires": {
+            "debug": "^2.2.0",
+            "es5-ext": "^0.10.50",
+            "nan": "^2.14.0",
+            "typedarray-to-buffer": "^3.1.5",
+            "yaeti": "^0.0.6"
+          }
+        }
       }
     },
     "web3-shh": {
@@ -6872,35 +6901,6 @@
         }
       }
     },
-    "websocket": {
-      "version": "github:web3-js/WebSocket-Node#905deb4812572b344f5801f8c9ce8bb02799d82e",
-      "from": "github:web3-js/WebSocket-Node#polyfill/globalThis",
-      "dev": true,
-      "requires": {
-        "debug": "^2.2.0",
-        "es5-ext": "^0.10.50",
-        "nan": "^2.14.0",
-        "typedarray-to-buffer": "^3.1.5",
-        "yaeti": "^0.0.6"
-      },
-      "dependencies": {
-        "debug": {
-          "version": "2.6.9",
-          "resolved": "https://registry.npmjs.org/debug/-/debug-2.6.9.tgz",
-          "integrity": "sha512-bC7ElrdJaJnPbAP+1EotYvqZsb3ecl5wi6Bfi6BJTUcNowp6cvspg0jXznRTKDjm/E7AdgFBVeAPVMNcKGsHMA==",
-          "dev": true,
-          "requires": {
-            "ms": "2.0.0"
-          }
-        },
-        "nan": {
-          "version": "2.14.0",
-          "resolved": "https://registry.npmjs.org/nan/-/nan-2.14.0.tgz",
-          "integrity": "sha512-INOFj37C7k3AfaNTtX8RhsTw7qRy7eLET14cROi9+5HAVbbHuIWUHEauBv5qT4Av2tWasiTY1Jw6puUNqRJXQg==",
-          "dev": true
-        }
-      }
-    },
     "which": {
       "version": "1.3.1",
       "resolved": "https://registry.npmjs.org/which/-/which-1.3.1.tgz",
diff --git a/package.json b/package.json
index 27d7317..46626a1 100644
--- a/package.json
+++ b/package.json
@@ -7,7 +7,7 @@
     "test": "test"
   },
   "dependencies": {
-    "@openzeppelin/contracts": "^2.4.0"
+    "@openzeppelin/contracts": "^4.4.2"
   },
   "devDependencies": {
     "prettier": "^1.19.1",