diff --git a/package.json b/package.json
index 057bfa1a3..346292437 100644
--- a/package.json
+++ b/package.json
@@ -52,6 +52,9 @@
     "v8-compile-cache": "^2.3.0",
     "which": "^4.0.0"
   },
+  "resolutions": {
+    "undici-types": "6.x"
+  },
   "scripts": {
     "build": "rm -rf dist shims && run build:bundle && ts-node ./mkshims.ts",
     "build:bundle": "esbuild ./sources/_lib.ts --bundle --platform=node --target=node18.17.0 --external:corepack --outfile='./dist/lib/corepack.cjs' --resolve-extensions='.ts,.mjs,.js'",
diff --git a/sources/httpUtils.ts b/sources/httpUtils.ts
index e995d1e99..5d5a667b1 100644
--- a/sources/httpUtils.ts
+++ b/sources/httpUtils.ts
@@ -92,6 +92,8 @@ export async function fetchUrlStream(input: string | URL, init?: RequestInit) {
   return stream;
 }
 
+let ProxyAgent: typeof import('undici').ProxyAgent;
+
 async function getProxyAgent(input: string | URL) {
   const {getProxyForUrl} = await import(`proxy-from-env`);
 
@@ -100,11 +102,20 @@ async function getProxyAgent(input: string | URL) {
 
   if (!proxy) return undefined;
 
-  // Doing a deep import here since undici isn't tree-shakeable
-  const {default: ProxyAgent} = (await import(
-    // @ts-expect-error No types for this specific file
-    `undici/lib/proxy-agent.js`
-  )) as { default: typeof import('undici').ProxyAgent };
+  if (ProxyAgent == null) {
+    // Doing a deep import here since undici isn't tree-shakeable
+    const [api, Dispatcher, _ProxyAgent] = await Promise.all([
+      // @ts-expect-error internal module is untyped
+      import(`undici/lib/api/index.js`),
+      // @ts-expect-error internal module is untyped
+      import(`undici/lib/dispatcher/dispatcher.js`),
+      // @ts-expect-error internal module is untyped
+      import(`undici/lib/dispatcher/proxy-agent.js`),
+    ]);
+
+    Object.assign(Dispatcher.default.prototype, api.default);
+    ProxyAgent = _ProxyAgent.default;
+  }
 
   return new ProxyAgent(proxy);
 }
diff --git a/tests/_registryServer.mjs b/tests/_registryServer.mjs
index eb3f1afd9..7f78f70c8 100644
--- a/tests/_registryServer.mjs
+++ b/tests/_registryServer.mjs
@@ -1,6 +1,7 @@
 import {createHash}   from 'node:crypto';
 import {once}         from 'node:events';
 import {createServer} from 'node:http';
+import {connect}      from 'node:net';
 import {gzipSync}     from 'node:zlib';
 
 function createSimpleTarArchive(fileName, fileContent, mode = 0o644) {
@@ -110,12 +111,47 @@ const server = createServer((req, res) => {
     res.writeHead(500).end(`Internal Error`);
     throw new Error(`unsupported request`, {cause: {url: req.url, packageName}});
   }
-}).listen(0, `localhost`);
+});
+
+if (process.env.AUTH_TYPE === `PROXY`) {
+  const proxy = createServer((req, res) => {
+    res.writeHead(200, {[`Content-Type`]: `text/plain`});
+    res.end(`okay`);
+  });
+  proxy.on(`connect`, (req, clientSocket, head) => {
+    if (req.url !== `example.com:80`) {
+      // Reject all requests except those to `example.com`
+      clientSocket.end(`HTTP/1.1 404 Not Found\r\n\r\n`);
+      return;
+    }
+    const {address, port} = server.address();
+    const serverSocket = connect(port, address, () => {
+      clientSocket.write(`HTTP/1.1 200 Connection Established\r\n` +
+      `Proxy-agent: Node.js-Proxy\r\n` +
+      `\r\n`);
+      serverSocket.write(head);
+      serverSocket.pipe(clientSocket);
+      clientSocket.pipe(serverSocket);
+    });
+  });
+  proxy.listen(0, `localhost`);
+  await once(proxy, `listening`);
+  const {address, port} = proxy.address();
+  process.env.ALL_PROXY = `http://${address.includes(`:`) ? `[${address}]` : address}:${port}`;
+
+  proxy.unref();
+}
 
+server.listen(0, `localhost`);
 await once(server, `listening`);
 
 const {address, port} = server.address();
 switch (process.env.AUTH_TYPE) {
+  case `PROXY`:
+    // The proxy set up above will redirect all requests to our custom registry,
+    process.env.COREPACK_NPM_REGISTRY = `http://user:pass@example.com`;
+    break;
+
   case `COREPACK_NPM_REGISTRY`:
     process.env.COREPACK_NPM_REGISTRY = `http://user:pass@${address.includes(`:`) ? `[${address}]` : address}:${port}`;
     break;
@@ -137,8 +173,11 @@ switch (process.env.AUTH_TYPE) {
 if (process.env.NOCK_ENV === `replay`) {
   const originalFetch = globalThis.fetch;
   globalThis.fetch = function fetch(i) {
-    if (!`${i}`.startsWith(`http://${address.includes(`:`) ? `[${address}]` : address}:${port}`))
-      throw new Error;
+    if (!`${i}`.startsWith(
+      process.env.AUTH_TYPE === `PROXY` ?
+        `http://example.com` :
+        `http://${address.includes(`:`) ? `[${address}]` : address}:${port}`))
+      throw new Error(`Unexpected request to  ${i}`);
 
     return Reflect.apply(originalFetch, this, arguments);
   };
diff --git a/tests/main.test.ts b/tests/main.test.ts
index 6d84e3fb2..ba01f1516 100644
--- a/tests/main.test.ts
+++ b/tests/main.test.ts
@@ -805,7 +805,7 @@ it(`should download yarn berry from custom registry`, async () => {
   });
 });
 
-for (const authType of [`COREPACK_NPM_REGISTRY`, `COREPACK_NPM_TOKEN`, `COREPACK_NPM_PASSWORD`]) {
+for (const authType of [`COREPACK_NPM_REGISTRY`, `COREPACK_NPM_TOKEN`, `COREPACK_NPM_PASSWORD`, `PROXY`]) {
   describe(`custom registry with auth ${authType}`, () => {
     beforeEach(() => {
       process.env.AUTH_TYPE = authType; // See `_registryServer.mjs`
diff --git a/yarn.lock b/yarn.lock
index 52596e862..8d39c265c 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -730,13 +730,6 @@ __metadata:
   languageName: node
   linkType: hard
 
-"@fastify/busboy@npm:^2.0.0":
-  version: 2.1.0
-  resolution: "@fastify/busboy@npm:2.1.0"
-  checksum: 10c0/7bb641080aac7cf01d88749ad331af10ba9ec3713ec07cabbe833908c75df21bd56249bb6173bdec07f5a41896b21e3689316f86684c06635da45f91ff4565a2
-  languageName: node
-  linkType: hard
-
 "@humanwhocodes/config-array@npm:^0.11.13":
   version: 0.11.13
   resolution: "@humanwhocodes/config-array@npm:0.11.13"
@@ -1303,11 +1296,11 @@ __metadata:
   linkType: hard
 
 "@types/node@npm:*, @types/node@npm:^20.4.6":
-  version: 20.10.5
-  resolution: "@types/node@npm:20.10.5"
+  version: 20.12.6
+  resolution: "@types/node@npm:20.12.6"
   dependencies:
     undici-types: "npm:~5.26.4"
-  checksum: 10c0/be30609aae0bfe492097815f166ccc07f465220cb604647fa4e5ec05a1d16c012a41b82b5f11ecfe2485cbb479d4d20384b95b809ca0bcff6d94d5bbafa645bb
+  checksum: 10c0/48ce732162cd6c02656aa5f996f0e695b57fdeb1ae762fbaa966afac2dcdcf52cb56be5ce1efb4babf8f97c2de545889aebc7f43c2e86f033487245c41fa1e6b
   languageName: node
   linkType: hard
 
@@ -5991,19 +5984,17 @@ __metadata:
   languageName: node
   linkType: hard
 
-"undici-types@npm:~5.26.4":
-  version: 5.26.5
-  resolution: "undici-types@npm:5.26.5"
-  checksum: 10c0/bb673d7876c2d411b6eb6c560e0c571eef4a01c1c19925175d16e3a30c4c428181fb8d7ae802a261f283e4166a0ac435e2f505743aa9e45d893f9a3df017b501
+"undici-types@npm:6.x":
+  version: 6.12.0
+  resolution: "undici-types@npm:6.12.0"
+  checksum: 10c0/439ad3a384b4b392ff7fbd98b50a29ea4ca0ca1899f29a967a043abb45f0e67a786b058f59a327b3007079cff35ed5337d20603f06b6bb6a5b27539ebecd9792
   languageName: node
   linkType: hard
 
 "undici@npm:^6.6.1":
-  version: 6.6.2
-  resolution: "undici@npm:6.6.2"
-  dependencies:
-    "@fastify/busboy": "npm:^2.0.0"
-  checksum: 10c0/c8c8a436059b13603f67ed4d917b4ba6d9ef282ac55c932c4790ee1a1c8cad1369da3c11b6e0b9df5a95ed1849cb98fa2f2310f6d0f9331dd359286c912497d2
+  version: 6.12.0
+  resolution: "undici@npm:6.12.0"
+  checksum: 10c0/5bbfd261ea20c8ed6bb3a22703acdae80cb40b1de0595a1c4df46f6602db78d7a387174c292c5640e339422acb1bfd1d2e0987ec086c057ccc24806edfd4688b
   languageName: node
   linkType: hard