diff --git a/packages/plugin-hardhat/CHANGELOG.md b/packages/plugin-hardhat/CHANGELOG.md
index 0a3689000..906b2a5e3 100644
--- a/packages/plugin-hardhat/CHANGELOG.md
+++ b/packages/plugin-hardhat/CHANGELOG.md
@@ -1,5 +1,9 @@
 # Changelog
 
+## Unreleased
+
+- Update dependency on undici. ([#948](https://github.com/OpenZeppelin/openzeppelin-upgrades/pull/948))
+
 ## 3.0.0 (2023-12-11)
 
 - Deploy proxies from OpenZeppelin Contracts 5.0. ([#919](https://github.com/OpenZeppelin/openzeppelin-upgrades/pull/919))
diff --git a/packages/plugin-hardhat/package.json b/packages/plugin-hardhat/package.json
index 9f4b01f06..08f171dcc 100644
--- a/packages/plugin-hardhat/package.json
+++ b/packages/plugin-hardhat/package.json
@@ -44,7 +44,7 @@
     "debug": "^4.1.1",
     "ethereumjs-util": "^7.1.5",
     "proper-lockfile": "^4.1.1",
-    "undici": "^5.14.0"
+    "undici": "^5.28.2"
   },
   "peerDependencies": {
     "@nomicfoundation/hardhat-ethers": "^3.0.0",
diff --git a/packages/plugin-hardhat/src/utils/etherscan-api.ts b/packages/plugin-hardhat/src/utils/etherscan-api.ts
index 33b510fa2..fe4843027 100644
--- a/packages/plugin-hardhat/src/utils/etherscan-api.ts
+++ b/packages/plugin-hardhat/src/utils/etherscan-api.ts
@@ -32,7 +32,7 @@ export async function callEtherscanApi(etherscan: Etherscan, params: any): Promi
   const responseBodyJson = await response.body.json();
   debug('Etherscan response', JSON.stringify(responseBodyJson));
 
-  return responseBodyJson;
+  return responseBodyJson as EtherscanResponseBody;
 }
 
 /**
@@ -64,7 +64,7 @@ interface EtherscanConfig {
 interface EtherscanResponseBody {
   status: string;
   message: string;
-  result: any;
+  result: unknown;
 }
 
 export const RESPONSE_OK = '1';
diff --git a/packages/plugin-hardhat/src/verify-proxy.ts b/packages/plugin-hardhat/src/verify-proxy.ts
index 773572b42..7e117c2bc 100644
--- a/packages/plugin-hardhat/src/verify-proxy.ts
+++ b/packages/plugin-hardhat/src/verify-proxy.ts
@@ -640,7 +640,7 @@ async function getEventResponse(
   const responseBody = await callEtherscanApi(etherscan, params);
 
   if (responseBody.status === RESPONSE_OK) {
-    const result = responseBody.result;
+    const result = responseBody.result as EtherscanEventResponse[];
     return result[0];
   } else if (responseBody.message === 'No records found' || responseBody.message === 'No logs found') {
     debug(`no result found for event topic ${topic} at address ${address}`);
@@ -697,7 +697,7 @@ async function linkProxyWithImplementationAbi(
 
   if (responseBody.status === RESPONSE_OK) {
     // initial call was OK, but need to send a status request using the returned guid to get the actual verification status
-    const guid = responseBody.result;
+    const guid = responseBody.result as string;
     responseBody = await checkProxyVerificationStatus(etherscan, guid);
 
     while (responseBody.result === 'Pending in queue') {
diff --git a/yarn.lock b/yarn.lock
index fb64bd349..9757abdb0 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -891,6 +891,11 @@
     "@ethersproject/properties" "^5.7.0"
     "@ethersproject/strings" "^5.7.0"
 
+"@fastify/busboy@^2.0.0":
+  version "2.1.0"
+  resolved "https://registry.yarnpkg.com/@fastify/busboy/-/busboy-2.1.0.tgz#0709e9f4cb252351c609c6e6d8d6779a8d25edff"
+  integrity sha512-+KpH+QxZU7O4675t3mnkQKcZZg56u+K/Ct2K+N2AZYNVK8kyeo/bI18tI8aPm3tvNNRyTWfj6s5tnGNlcbQRsA==
+
 "@frangio/servbot@^0.2.5":
   version "0.2.5"
   resolved "https://registry.yarnpkg.com/@frangio/servbot/-/servbot-0.2.5.tgz#d4524c15c8a34fcdde36037b84407c4c60b4cf16"
@@ -12506,6 +12511,13 @@ undici@^5.14.0:
   dependencies:
     busboy "^1.6.0"
 
+undici@^5.28.2:
+  version "5.28.2"
+  resolved "https://registry.yarnpkg.com/undici/-/undici-5.28.2.tgz#fea200eac65fc7ecaff80a023d1a0543423b4c91"
+  integrity sha512-wh1pHJHnUeQV5Xa8/kyQhO7WFa8M34l026L5P/+2TYiakvGy5Rdc8jWZVyG7ieht/0WgJLEd3kcU5gKx+6GC8w==
+  dependencies:
+    "@fastify/busboy" "^2.0.0"
+
 unfetch@^4.2.0:
   version "4.2.0"
   resolved "https://registry.yarnpkg.com/unfetch/-/unfetch-4.2.0.tgz#7e21b0ef7d363d8d9af0fb929a5555f6ef97a3be"