diff --git a/.changeset/three-penguins-trade.md b/.changeset/three-penguins-trade.md
new file mode 100644
index 0000000000..9f7f20d30f
--- /dev/null
+++ b/.changeset/three-penguins-trade.md
@@ -0,0 +1,6 @@
+---
+"@pnpm/network.auth-header": patch
+"pnpm": patch
+---
+
+Fix missing auth tokens in registries with paths specified (e.g. //npm.pkg.github.com/pnpm). #5970 #2933
diff --git a/network/auth-header/src/index.ts b/network/auth-header/src/index.ts
index bdd5ec4d48..240c032cfc 100644
--- a/network/auth-header/src/index.ts
+++ b/network/auth-header/src/index.ts
@@ -24,6 +24,9 @@ function getMaxParts (uris: string[]) {
 }
 
 function getAuthHeaderByURI (authHeaders: Record<string, string>, maxParts: number, uri: string): string | undefined {
+  if (!uri.endsWith('/')) {
+    uri += '/'
+  }
   const nerfed = nerfDart(uri)
   const parts = nerfed.split('/')
   for (let i = Math.min(parts.length, maxParts) - 1; i >= 3; i--) {
@@ -35,4 +38,4 @@ function getAuthHeaderByURI (authHeaders: Record<string, string>, maxParts: numb
     return getAuthHeaderByURI(authHeaders, maxParts, urlWithoutPort)
   }
   return undefined
-}
\ No newline at end of file
+}
diff --git a/network/auth-header/test/getAuthHeaderByURI.ts b/network/auth-header/test/getAuthHeaderByURI.ts
index 851dfbba1a..706bc7263e 100644
--- a/network/auth-header/test/getAuthHeaderByURI.ts
+++ b/network/auth-header/test/getAuthHeaderByURI.ts
@@ -43,3 +43,21 @@ test('getAuthHeaderByURI() when default ports are specified', () => {
 test('returns undefined when the auth header is not found', () => {
   expect(createGetAuthHeaderByURI({ allSettings: {}, userSettings: {} })('http://reg.com')).toBe(undefined)
 })
+
+test('getAuthHeaderByURI() when the registry has pathnames', () => {
+  const getAuthHeaderByURI = createGetAuthHeaderByURI({
+    allSettings: {
+      '//npm.pkg.github.com/pnpm/:_authToken': 'abc123',
+    },
+    userSettings: {},
+  })
+  expect(getAuthHeaderByURI('https://npm.pkg.github.com/pnpm')).toBe('Bearer abc123')
+  expect(getAuthHeaderByURI('https://npm.pkg.github.com/pnpm/')).toBe('Bearer abc123')
+  expect(getAuthHeaderByURI('https://npm.pkg.github.com/pnpm/foo')).toBe('Bearer abc123')
+  expect(getAuthHeaderByURI('https://npm.pkg.github.com/pnpm/foo/')).toBe('Bearer abc123')
+  expect(getAuthHeaderByURI('https://npm.pkg.github.com/pnpm/foo/-/foo-1.0.0.tgz')).toBe('Bearer abc123')
+  expect(getAuthHeaderByURI('https://npm.pkg.github.com/pnpm/foo/-/foo-1.0.0.tgz')).toBe('Bearer abc123')
+  expect(getAuthHeaderByURI('https://npm.pkg.github.com/pnpm/foo/-/foo-1.0.0.tgz')).toBe('Bearer abc123')
+  expect(getAuthHeaderByURI('https://npm.pkg.github.com/pnpm/foo/-/foo-1.0.0.tgz')).toBe('Bearer abc123')
+  expect(getAuthHeaderByURI('https://npm.pkg.github.com/pnpm/foo/-/foo-1.0.0.tgz')).toBe('Bearer abc123')
+})
\ No newline at end of file