diff --git a/src/__tests__/options-get-iterator-method.spec-d.ts b/src/__tests__/options-get-iterator-method.spec-d.ts
new file mode 100644
index 0000000..096d8f7
--- /dev/null
+++ b/src/__tests__/options-get-iterator-method.spec-d.ts
@@ -0,0 +1,17 @@
+/**
+ * @file Type Tests - GetIteratorMethodOptions
+ * @module aggregate-error-ponyfill/tests/unit-d/GetIteratorMethodOptions
+ */
+
+import type getIteratorMethod from 'es-abstract/helpers/getIteratorMethod'
+import type TestSubject from '../options-get-iterator-method'
+
+describe('unit-d:GetIteratorMethodOptions', () => {
+  it('should equal Parameters<typeof getIteratorMethod>["0"]', () => {
+    // Arrange
+    type Expected = Parameters<typeof getIteratorMethod>['0']
+
+    // Expect
+    expectTypeOf<TestSubject>().toEqualTypeOf<Expected>
+  })
+})
diff --git a/src/__tests__/options.spec-d.ts b/src/__tests__/options.spec-d.ts
new file mode 100644
index 0000000..6aa9300
--- /dev/null
+++ b/src/__tests__/options.spec-d.ts
@@ -0,0 +1,19 @@
+/**
+ * @file Type Tests - Options
+ * @module aggregate-error-ponyfill/tests/unit-d/Options
+ */
+
+import type { KeysRequired } from '@flex-development/tutils'
+import type TestSubject from '../options'
+
+describe('unit-d:Options', () => {
+  it('should allow empty object', () => {
+    expectTypeOf<KeysRequired<TestSubject>>().toBeNever()
+  })
+
+  it('should match [cause?: Cause | undefined]', () => {
+    expectTypeOf<TestSubject>()
+      .toHaveProperty('cause')
+      .toEqualTypeOf<unknown | undefined>()
+  })
+})
diff --git a/src/__tests__/ponyfill.spec-d.ts b/src/__tests__/ponyfill.spec-d.ts
new file mode 100644
index 0000000..73a3adc
--- /dev/null
+++ b/src/__tests__/ponyfill.spec-d.ts
@@ -0,0 +1,24 @@
+/**
+ * @file Type Tests - AggregateError
+ * @module aggregate-error-ponyfill/tests/unit-d/AggregateError
+ */
+
+import type TestSubject from '../ponyfill'
+
+describe('unit-d:AggregateError', () => {
+  it('should extend Error', () => {
+    expectTypeOf<TestSubject>().toMatchTypeOf<Error>()
+  })
+
+  it('should match [cause?: Cause | undefined]', () => {
+    expectTypeOf<TestSubject<any, string>>()
+      .toHaveProperty('cause')
+      .toEqualTypeOf<string | undefined>()
+  })
+
+  it('should match [errors: T[]]', () => {
+    expectTypeOf<TestSubject<Error | string>>()
+      .toHaveProperty('errors')
+      .toEqualTypeOf<(Error | string)[]>()
+  })
+})
diff --git a/src/__tests__/ponyfill.spec.ts b/src/__tests__/ponyfill.spec.ts
index 4d4bb89..086c9bf 100644
--- a/src/__tests__/ponyfill.spec.ts
+++ b/src/__tests__/ponyfill.spec.ts
@@ -1,11 +1,11 @@
 /**
- * @file Unit Tests - ponyfill
- * @module aggregate-error-ponyfill/tests/unit/ponyfill
+ * @file Unit Tests - AggregateError
+ * @module aggregate-error-ponyfill/tests/unit/AggregateError
  */
 
 import TestSubject from '../ponyfill'
 
-describe('unit:ponyfill', () => {
+describe('unit:AggregateError', () => {
   it('should create spec-compliant AggregateError', () => {
     // Arrange
     const cause = new Error('The server responded with a 500 status')
diff --git a/src/options-get-iterator-method.ts b/src/options-get-iterator-method.ts
index cb2fea8..b9e6416 100644
--- a/src/options-get-iterator-method.ts
+++ b/src/options-get-iterator-method.ts
@@ -1,6 +1,6 @@
 /**
  * @file AggregateError - GetIteratorMethodOptions
- * @module aggregate-error-ponyfill/ponyfill/GetIteratorMethodOptions
+ * @module aggregate-error-ponyfill/GetIteratorMethodOptions
  */
 
 import type getIteratorMethod from 'es-abstract/helpers/getIteratorMethod'
diff --git a/src/options.ts b/src/options.ts
index b11915c..fe18ace 100644
--- a/src/options.ts
+++ b/src/options.ts
@@ -1,6 +1,6 @@
 /**
  * @file AggregateError - Options
- * @module aggregate-error-ponyfill/ponyfill/Options
+ * @module aggregate-error-ponyfill/Options
  */
 
 /**
@@ -19,7 +19,7 @@ interface Options<Cause = unknown> {
    *
    * @see https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Error/cause
    */
-  cause?: Cause
+  cause?: Cause | undefined
 }
 
 export type { Options as default }
diff --git a/src/ponyfill.ts b/src/ponyfill.ts
index 939347a..02a7c78 100644
--- a/src/ponyfill.ts
+++ b/src/ponyfill.ts
@@ -1,6 +1,6 @@
 /**
- * @file AggregateError - Ponyfill
- * @module aggregate-error-ponyfill/ponyfill
+ * @file AggregateError
+ * @module aggregate-error-ponyfill/AggregateError
  */
 
 import AdvanceStringIndex from 'es-abstract/2021/AdvanceStringIndex'
@@ -26,21 +26,21 @@ import type GetIteratorMethodOptions from './options-get-iterator-method'
  * @see https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/AggregateError
  *
  * @template T - Aggregated error type
- * @template C - Error cause type
+ * @template Cause - Error cause type
  *
  * @class
  * @extends {Error}
  */
-class AggregateError<T = any, C = unknown> extends Error {
+class AggregateError<T = any, Cause = unknown> extends Error {
   /**
    * Error cause.
    *
    * @see https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Error/cause
    *
    * @public
-   * @member {C | undefined} cause
+   * @member {Cause | undefined} cause
    */
-  public cause?: C
+  public cause?: Cause | undefined
 
   /**
    * @public
@@ -67,10 +67,10 @@ class AggregateError<T = any, C = unknown> extends Error {
    *
    * @param {Iterable<T>} errors - An iterable of errors
    * @param {string} [message] - Human-readable description of the error
-   * @param {Options<C>} [options] - Error options
-   * @param {C} [options.cause] - The original cause of the error
+   * @param {Options<Cause>} [options] - Error options
+   * @param {Cause} [options.cause] - The original cause of the error
    */
-  constructor(errors: Iterable<T>, message?: string, options?: Options<C>) {
+  constructor(errors: Iterable<T>, message?: string, options?: Options<Cause>) {
     super(message)
 
     /**