diff --git a/packages/node-loader/index.js b/packages/node-loader/index.js
index 67d01f4be..877ce08f5 100644
--- a/packages/node-loader/index.js
+++ b/packages/node-loader/index.js
@@ -4,7 +4,7 @@
 
 import {createLoader} from './lib/index.js'
 
-const {getFormat, load, transformSource} = createLoader()
+const defaultLoader = createLoader()
 
-export {getFormat, load, transformSource}
 export {createLoader} from './lib/index.js'
+export const load = defaultLoader.load
diff --git a/packages/node-loader/lib/index.js b/packages/node-loader/lib/index.js
index 3530fb42a..860f57c18 100644
--- a/packages/node-loader/lib/index.js
+++ b/packages/node-loader/lib/index.js
@@ -8,7 +8,7 @@ import {extnamesToRegex} from '@mdx-js/mdx/lib/util/extnames-to-regex.js'
 import {VFile} from 'vfile'
 
 /**
- * Create smart processors to handle different formats.
+ * Create a loader to handle markdown and MDX.
  *
  * @param {Readonly<Options> | null | undefined} [options]
  *   Configuration (optional).
@@ -20,9 +20,8 @@ export function createLoader(options) {
   const {extnames, process} = createFormatAwareProcessors(options_)
   const regex = extnamesToRegex(extnames)
 
-  return {load, getFormat, transformSource}
+  return {load}
 
-  // Node version 17.
   /**
    * @param {string} href
    *   URL.
@@ -45,51 +44,4 @@ export function createLoader(options) {
 
     return defaultLoad(href, context, defaultLoad)
   }
-
-  // To do: remove.
-  /* c8 ignore start */
-  // Pre version 17.
-  /**
-   * @param {string} href
-   *   URL.
-   * @param {unknown} context
-   *   Context.
-   * @param {Function} defaultGetFormat
-   *   Default `getFormat` function.
-   * @deprecated
-   *   This is an obsolete legacy function that no longer works in Node 17.
-   * @returns
-   *   Result.
-   */
-  function getFormat(href, context, defaultGetFormat) {
-    const url = new URL(href)
-
-    return url.protocol === 'file:' && regex.test(url.pathname)
-      ? {format: 'module'}
-      : defaultGetFormat(href, context, defaultGetFormat)
-  }
-
-  /**
-   * @param {string} value
-   *   Code.
-   * @param {{url: string, [x: string]: unknown}} context
-   *   Context.
-   * @param {Function} defaultTransformSource
-   *   Default `transformSource` function.
-   * @deprecated
-   *   This is an obsolete legacy function that no longer works in Node 17.
-   * @returns
-   *   Result.
-   */
-  async function transformSource(value, context, defaultTransformSource) {
-    const url = new URL(context.url)
-
-    if (url.protocol === 'file:' && regex.test(url.pathname)) {
-      const file = await process(new VFile({path: new URL(context.url), value}))
-      return {source: String(file)}
-    }
-
-    return defaultTransformSource(value, context, defaultTransformSource)
-  }
-  /* c8 ignore end */
 }
diff --git a/packages/node-loader/readme.md b/packages/node-loader/readme.md
index 0fd67555c..84674640b 100644
--- a/packages/node-loader/readme.md
+++ b/packages/node-loader/readme.md
@@ -119,10 +119,9 @@ One extra field is supported:
 ```tsx
 import {createLoader} from '@mdx-js/node-loader'
 
-// Load is for Node 17+, the rest for 12-16.
-const {getFormat, load, transformSource} = createLoader(/* Options… */)
+const {load} = createLoader(/* Options… */)
 
-export {getFormat, load, transformSource}
+export {load}
 ```
 
 This example can then be used with `node --experimental-loader=./my-loader.js`.
diff --git a/packages/node-loader/test/index.js b/packages/node-loader/test/index.js
index e01b11b17..52fb2e24f 100644
--- a/packages/node-loader/test/index.js
+++ b/packages/node-loader/test/index.js
@@ -12,9 +12,7 @@ test('@mdx-js/node-loader', async function (t) {
   await t.test('should expose the public api', async function () {
     assert.deepEqual(Object.keys(await import('@mdx-js/node-loader')).sort(), [
       'createLoader',
-      'getFormat',
-      'load',
-      'transformSource'
+      'load'
     ])
   })
 
diff --git a/script/jsx-loader.js b/script/jsx-loader.js
index 877356416..47ad40c08 100644
--- a/script/jsx-loader.js
+++ b/script/jsx-loader.js
@@ -2,18 +2,16 @@ import fs from 'node:fs/promises'
 import {fileURLToPath} from 'node:url'
 import {transform} from 'esbuild'
 
-// To do: remove Node 16 version.
-const {getFormat, load, transformSource} = createLoader()
+const {load} = createLoader()
 
-export {getFormat, load, transformSource}
+export {load}
 
 /**
  * A tiny JSX loader.
  */
 export function createLoader() {
-  return {getFormat, load, transformSource}
+  return {load}
 
-  // Node version 17.
   /**
    * @param {string} href
    *   URL.
@@ -48,58 +46,4 @@ export function createLoader() {
 
     return {format: 'module', shortCircuit: true, source: code}
   }
-
-  // Pre version 17.
-  /**
-   * @param {string} href
-   *   URL.
-   * @param {unknown} context
-   *   Context.
-   * @param {Function} defaultGetFormat
-   *   Default `getFormat`.
-   * @returns
-   *   Result.
-   */
-  function getFormat(href, context, defaultGetFormat) {
-    const url = new URL(href)
-
-    return url.pathname.endsWith('.jsx')
-      ? {format: 'module'}
-      : defaultGetFormat(href, context, defaultGetFormat)
-  }
-
-  /**
-   * @param {Buffer} value
-   *   Code.
-   * @param {{url: string, [x: string]: unknown}} context
-   *   Context.
-   * @param {Function} defaultTransformSource
-   *   Default `transformSource`.
-   * @returns
-   *   Result.
-   */
-  async function transformSource(value, context, defaultTransformSource) {
-    const url = new URL(context.url)
-
-    if (!url.pathname.endsWith('.jsx')) {
-      return defaultTransformSource(value, context, defaultTransformSource)
-    }
-
-    const {code, warnings} = await transform(String(value), {
-      format: context.format === 'module' ? 'esm' : 'cjs',
-      loader: 'jsx',
-      sourcefile: fileURLToPath(url),
-      sourcemap: 'both',
-      target: 'esnext'
-    })
-
-    if (warnings) {
-      for (const warning of warnings) {
-        console.log(warning.location)
-        console.log(warning.text)
-      }
-    }
-
-    return {source: code}
-  }
 }