diff --git a/package-lock.json b/package-lock.json
index 06624d39f..675c45b5e 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -5135,9 +5135,9 @@
       }
     },
     "node_modules/estree-util-build-jsx": {
-      "version": "3.0.0",
-      "resolved": "https://registry.npmjs.org/estree-util-build-jsx/-/estree-util-build-jsx-3.0.0.tgz",
-      "integrity": "sha512-mIxOqyNfkwCz7MU7d8Hd0meGj+Vnn2U06mGuUkPTPlNumBfM1gqL2OlC+rB+QgRAmodoUGaHK5GgqoKQ0T8QRw==",
+      "version": "3.0.1",
+      "resolved": "https://registry.npmjs.org/estree-util-build-jsx/-/estree-util-build-jsx-3.0.1.tgz",
+      "integrity": "sha512-8U5eiL6BTrPxp/CHbs2yMgP8ftMhR5ww1eIKoWRMlqvltHF8fZn5LRDvTKuxD3DUn+shRbLGqXemcP51oFCsGQ==",
       "dependencies": {
         "@types/estree-jsx": "^1.0.0",
         "devlop": "^1.0.0",
diff --git a/packages/mdx/lib/plugin/recma-jsx-build.js b/packages/mdx/lib/plugin/recma-jsx-build.js
index 1bc81495c..58192166c 100644
--- a/packages/mdx/lib/plugin/recma-jsx-build.js
+++ b/packages/mdx/lib/plugin/recma-jsx-build.js
@@ -46,20 +46,37 @@ export function recmaJsxBuild(options) {
     // When compiling to a function body, replace the import that was just
     // generated, and get `jsx`, `jsxs`, and `Fragment` from `arguments[0]`
     // instead.
-    if (
-      outputFormat === 'function-body' &&
-      tree.body[0] &&
-      tree.body[0].type === 'ImportDeclaration' &&
-      typeof tree.body[0].source.value === 'string' &&
-      /\/jsx-(dev-)?runtime$/.test(tree.body[0].source.value)
-    ) {
-      tree.body[0] = {
-        type: 'VariableDeclaration',
-        kind: 'const',
-        declarations: specifiersToDeclarations(
-          tree.body[0].specifiers,
-          toIdOrMemberExpression(['arguments', 0])
-        )
+    if (outputFormat === 'function-body') {
+      let index = 0
+
+      // Skip directives: JS currently only has `use strict`, but Acorn allows
+      // arbitrary ones.
+      // Practically things like `use client` could be used?
+      while (index < tree.body.length) {
+        const child = tree.body[index]
+        if ('directive' in child && child.directive) {
+          index++
+        } else {
+          break
+        }
+      }
+
+      const declaration = tree.body[index]
+
+      if (
+        declaration &&
+        declaration.type === 'ImportDeclaration' &&
+        typeof declaration.source.value === 'string' &&
+        /\/jsx-(dev-)?runtime$/.test(declaration.source.value)
+      ) {
+        tree.body[index] = {
+          type: 'VariableDeclaration',
+          kind: 'const',
+          declarations: specifiersToDeclarations(
+            declaration.specifiers,
+            toIdOrMemberExpression(['arguments', 0])
+          )
+        }
       }
     }
   }
diff --git a/packages/mdx/lib/plugin/recma-jsx-rewrite.js b/packages/mdx/lib/plugin/recma-jsx-rewrite.js
index db93bf60e..818053d56 100644
--- a/packages/mdx/lib/plugin/recma-jsx-rewrite.js
+++ b/packages/mdx/lib/plugin/recma-jsx-rewrite.js
@@ -560,6 +560,14 @@ export function recmaJsxRewrite(options) {
         }
       })
     }
+
+    if (outputFormat === 'function-body') {
+      tree.body.unshift({
+        type: 'ExpressionStatement',
+        expression: {type: 'Literal', value: 'use strict'},
+        directive: 'use strict'
+      })
+    }
   }
 }
 
diff --git a/packages/mdx/test/syntax.js b/packages/mdx/test/syntax.js
index 43996a768..5ae661ef1 100644
--- a/packages/mdx/test/syntax.js
+++ b/packages/mdx/test/syntax.js
@@ -899,4 +899,40 @@ test('@mdx-js/mdx: syntax: MDX (ESM)', async function (t) {
       ].join('\n')
     )
   })
+
+  await t.test(
+    "should add a 'use strict' when generating a `function-body`",
+    async function () {
+      assert.equal(
+        String(await compile('# hi', {outputFormat: 'function-body'})),
+        [
+          '/*@jsxRuntime automatic @jsxImportSource react*/',
+          '"use strict";',
+          'const {jsx: _jsx} = arguments[0];',
+          'function _createMdxContent(props) {',
+          '  const _components = {',
+          '    h1: "h1",',
+          '    ...props.components',
+          '  };',
+          '  return _jsx(_components.h1, {',
+          '    children: "hi"',
+          '  });',
+          '}',
+          'function MDXContent(props = {}) {',
+          '  const {wrapper: MDXLayout} = props.components || ({});',
+          '  return MDXLayout ? _jsx(MDXLayout, {',
+          '    ...props,',
+          '    children: _jsx(_createMdxContent, {',
+          '      ...props',
+          '    })',
+          '  }) : _createMdxContent(props);',
+          '}',
+          'return {',
+          '  default: MDXContent',
+          '};',
+          ''
+        ].join('\n')
+      )
+    }
+  )
 })