diff --git a/packages/next/src/build/index.ts b/packages/next/src/build/index.ts
index de697e95455d..da2e9274a13c 100644
--- a/packages/next/src/build/index.ts
+++ b/packages/next/src/build/index.ts
@@ -1251,22 +1251,25 @@ export default async function build(
       let middlewareFilePath: string | undefined
 
       for (const rootPath of rootPaths) {
-        const { name: fileBaseName, dir: fileDir } = path.parse(rootPath)
+        const { base: fileBase, dir: fileDir } = path.parse(rootPath)
 
         const normalizedFileDir = normalizePathSep(fileDir)
         const isAtConventionLevel =
           normalizedFileDir === '/' || normalizedFileDir === '/src'
 
-        if (isAtConventionLevel && fileBaseName === MIDDLEWARE_FILENAME) {
+        if (!isAtConventionLevel) continue
+
+        // Use the same regexes that filtered `rootPaths` above to assign each
+        // matched file to its convention bucket. Comparing against the bare
+        // `path.parse(...).name` would miss files using a multi-segment
+        // custom `pageExtensions` entry such as `'universal.ts'`, because
+        // `path.parse('/instrumentation.universal.ts').name` is
+        // `'instrumentation.universal'` — not `INSTRUMENTATION_HOOK_FILENAME`.
+        if (middlewareDetectionRegExp.test(fileBase)) {
           middlewareFilePath = rootPath
-        }
-        if (isAtConventionLevel && fileBaseName === PROXY_FILENAME) {
+        } else if (proxyDetectionRegExp.test(fileBase)) {
           proxyFilePath = rootPath
-        }
-        if (
-          isAtConventionLevel &&
-          fileBaseName === INSTRUMENTATION_HOOK_FILENAME
-        ) {
+        } else if (instrumentationHookDetectionRegExp.test(fileBase)) {
           instrumentationHookFilePath = rootPath
         }
       }
diff --git a/test/integration/instrumentation-page-extensions/app/next.config.js b/test/integration/instrumentation-page-extensions/app/next.config.js
new file mode 100644
index 000000000000..d9b311567596
--- /dev/null
+++ b/test/integration/instrumentation-page-extensions/app/next.config.js
@@ -0,0 +1,4 @@
+/** @type {import('next').NextConfig} */
+module.exports = {
+  pageExtensions: ['ts', 'tsx', 'js', 'jsx', 'universal.ts', 'universal.tsx'],
+}
diff --git a/test/integration/instrumentation-page-extensions/app/src/instrumentation.universal.ts b/test/integration/instrumentation-page-extensions/app/src/instrumentation.universal.ts
new file mode 100644
index 000000000000..cd2d2a2f3e48
--- /dev/null
+++ b/test/integration/instrumentation-page-extensions/app/src/instrumentation.universal.ts
@@ -0,0 +1,5 @@
+export function register() {
+  // Marker so the test can confirm the build picked the hook up; in
+  // practice, just compiling `instrumentation.js` into `.next/server/`
+  // is the signal we assert on.
+}
diff --git a/test/integration/instrumentation-page-extensions/app/src/pages/index.tsx b/test/integration/instrumentation-page-extensions/app/src/pages/index.tsx
new file mode 100644
index 000000000000..051969f4dd15
--- /dev/null
+++ b/test/integration/instrumentation-page-extensions/app/src/pages/index.tsx
@@ -0,0 +1,3 @@
+export default function Page() {
+  return <p>hello</p>
+}
diff --git a/test/integration/instrumentation-page-extensions/app/tsconfig.json b/test/integration/instrumentation-page-extensions/app/tsconfig.json
new file mode 100644
index 000000000000..4ef6da7de289
--- /dev/null
+++ b/test/integration/instrumentation-page-extensions/app/tsconfig.json
@@ -0,0 +1,19 @@
+{
+  "compilerOptions": {
+    "target": "ES2017",
+    "lib": ["dom", "dom.iterable", "esnext"],
+    "allowJs": true,
+    "skipLibCheck": true,
+    "strict": false,
+    "noEmit": true,
+    "incremental": true,
+    "module": "esnext",
+    "esModuleInterop": true,
+    "moduleResolution": "bundler",
+    "resolveJsonModule": true,
+    "isolatedModules": true,
+    "jsx": "react-jsx"
+  },
+  "include": ["next-env.d.ts", "**/*.mts", "**/*.ts", "**/*.tsx"],
+  "exclude": ["node_modules"]
+}
diff --git a/test/integration/instrumentation-page-extensions/test/index.test.ts b/test/integration/instrumentation-page-extensions/test/index.test.ts
new file mode 100644
index 000000000000..1e01eca45ef9
--- /dev/null
+++ b/test/integration/instrumentation-page-extensions/test/index.test.ts
@@ -0,0 +1,36 @@
+/* eslint-env jest */
+
+import { existsSync } from 'fs'
+import { join } from 'path'
+import { nextBuild } from 'next-test-utils'
+
+const appDir = join(__dirname, '../app')
+
+describe('instrumentation hook detection with custom multi-segment pageExtensions', () => {
+  ;(process.env.IS_TURBOPACK_TEST ? describe.skip : describe)(
+    'production mode (webpack)',
+    () => {
+      it('compiles src/instrumentation.universal.ts when it matches pageExtensions', async () => {
+        const result = await nextBuild(appDir, undefined, {
+          cwd: appDir,
+          stderr: true,
+          stdout: true,
+        })
+        expect(result.code).toBe(0)
+
+        // If the hook was detected, the build emits the compiled
+        // instrumentation entry to `.next/server/instrumentation.js`.
+        // Before the fix for #92342, custom multi-segment pageExtensions
+        // (e.g. `universal.ts`) caused the file to be matched by the
+        // detection regex but then dropped because
+        // `path.parse('instrumentation.universal.ts').name` is
+        // `'instrumentation.universal'` — not `'instrumentation'` — so
+        // the equality check against `INSTRUMENTATION_HOOK_FILENAME`
+        // failed and `instrumentation.js` was never produced.
+        expect(
+          existsSync(join(appDir, '.next/server/instrumentation.js'))
+        ).toBe(true)
+      })
+    }
+  )
+})