diff --git a/.gitignore b/.gitignore
index 388388c..8123c9e 100644
--- a/.gitignore
+++ b/.gitignore
@@ -6,3 +6,4 @@
 coverage/
 node_modules/
 yarn.lock
+!/index.d.ts
diff --git a/index.d.ts b/index.d.ts
new file mode 100644
index 0000000..0f75a31
--- /dev/null
+++ b/index.d.ts
@@ -0,0 +1,13 @@
+import type {Options as MicromarkOptions} from 'micromark-extension-gfm'
+import type {Options as MdastOptions} from 'mdast-util-gfm'
+
+export {default} from './lib/index.js'
+
+/**
+ * Configuration for `remark-gfm`.
+ *
+ * Currently supports `singleTilde` as a parse option and
+ * `tableCellPadding`, `tablePipeAlign`, and `stringLength` as
+ * a serialization option.
+ */
+export interface Options extends MicromarkOptions, MdastOptions {}
diff --git a/index.js b/index.js
index a49a278..6a4c25d 100644
--- a/index.js
+++ b/index.js
@@ -1,5 +1,2 @@
-/**
- * @typedef {import('./lib/index.js').Options} Options
- */
-
+// Note: types exposed from `index.d.ts`.
 export {default} from './lib/index.js'
diff --git a/lib/index.js b/lib/index.js
index 2205580..ee1cca2 100644
--- a/lib/index.js
+++ b/lib/index.js
@@ -1,17 +1,11 @@
 /**
- * @import {Options as MdastOptions} from 'mdast-util-gfm'
  * @import {Root} from 'mdast'
- * @import {Options as MicromarkOptions} from 'micromark-extension-gfm'
+ * @import {Options} from 'remark-gfm'
  * @import {} from 'remark-parse'
  * @import {} from 'remark-stringify'
  * @import {Processor} from 'unified'
  */
 
-/**
- * @typedef {MicromarkOptions & MdastOptions} Options
- *   Configuration.
- */
-
 import {gfmFromMarkdown, gfmToMarkdown} from 'mdast-util-gfm'
 import {gfm} from 'micromark-extension-gfm'
 
diff --git a/package.json b/package.json
index 306d906..17831d7 100644
--- a/package.json
+++ b/package.json
@@ -29,7 +29,6 @@
   },
   "exports": "./index.js",
   "files": [
-    "index.d.ts.map",
     "index.d.ts",
     "index.js",
     "lib/"
@@ -86,6 +85,29 @@
   "version": "4.0.0",
   "xo": {
     "overrides": [
+      {
+        "files": [
+          "**/*.d.ts"
+        ],
+        "rules": {
+          "@typescript-eslint/array-type": [
+            "error",
+            {
+              "default": "generic"
+            }
+          ],
+          "@typescript-eslint/ban-types": [
+            "error",
+            {
+              "extendDefaults": true
+            }
+          ],
+          "@typescript-eslint/consistent-type-definitions": [
+            "error",
+            "interface"
+          ]
+        }
+      },
       {
         "files": [
           "test/**/*.js"
diff --git a/tsconfig.json b/tsconfig.json
index fc3d1e4..c3e0c82 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -12,5 +12,5 @@
     "target": "es2022"
   },
   "exclude": ["coverage/", "node_modules/"],
-  "include": ["**/*.js"]
+  "include": ["**/*.js", "index.d.ts"]
 }