diff --git a/contracts/package.json b/contracts/package.json
index 3e5c158..c19f136 100644
--- a/contracts/package.json
+++ b/contracts/package.json
@@ -13,7 +13,7 @@
     "deploy:xdai": "hardhat deploy --network xdai"
   },
   "dependencies": {
-    "@openzeppelin/contracts": "^3.4.0"
+    "@openzeppelin/contracts": "^4.4.1"
   },
   "devDependencies": {
     "@nomiclabs/hardhat-ethers": "^2.0.1",
diff --git a/yarn.lock b/yarn.lock
index d1d4017..b7c6b5a 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -1955,10 +1955,10 @@
     "@types/sinon-chai" "^3.2.3"
     "@types/web3" "1.0.19"
 
-"@openzeppelin/contracts@^3.4.0":
-  version "3.4.0"
-  resolved "https://registry.yarnpkg.com/@openzeppelin/contracts/-/contracts-3.4.0.tgz#9a1669ad5f9fdfb6e273bb5a4fed10cb4cc35eb0"
-  integrity sha512-qh+EiHWzfY/9CORr+eRUkeEUP1WiFUcq3974bLHwyYzLBUtK6HPaMkIUHi74S1rDTZ0sNz42DwPc5A4IJvN3rg==
+"@openzeppelin/contracts@^4.4.1":
+  version "4.4.1"
+  resolved "https://registry.yarnpkg.com/@openzeppelin/contracts/-/contracts-4.4.1.tgz#3382db2cd83ab565ed9626765e7da92944b45de8"
+  integrity sha512-o+pHCf/yMLSlV5MkDQEzEQL402i6SoRnktru+0rdSxVEFZcTzzGhZCAtZjUFyKGazMSv1TilzMg+RbED1N8XHQ==
 
 "@resolver-engine/core@^0.3.3":
   version "0.3.3"