diff --git a/packages/@headlessui-react/src/components/combobox/combobox.test.tsx b/packages/@headlessui-react/src/components/combobox/combobox.test.tsx
index fd33475de..34a3eac92 100644
--- a/packages/@headlessui-react/src/components/combobox/combobox.test.tsx
+++ b/packages/@headlessui-react/src/components/combobox/combobox.test.tsx
@@ -39,6 +39,7 @@ import {
   assertCombobox,
   ComboboxMode,
   assertNotActiveComboboxOption,
+  assertComboboxInput,
 } from '../../test-utils/accessibility-assertions'
 import { Transition } from '../transitions/transition'
 
@@ -296,8 +297,11 @@ describe('Rendering', () => {
 
         render(<Example />)
 
+        assertComboboxInput({ state: ComboboxState.InvisibleUnmounted })
+
         await click(getComboboxButton())
 
+        assertComboboxInput({ state: ComboboxState.Visible })
         assertComboboxList({ state: ComboboxState.Visible })
 
         await click(getComboboxOptions()[1])
diff --git a/packages/@headlessui-react/src/test-utils/accessibility-assertions.ts b/packages/@headlessui-react/src/test-utils/accessibility-assertions.ts
index 6eba1d4c1..37db4db69 100644
--- a/packages/@headlessui-react/src/test-utils/accessibility-assertions.ts
+++ b/packages/@headlessui-react/src/test-utils/accessibility-assertions.ts
@@ -330,6 +330,57 @@ export function assertCombobox(
   }
 }
 
+export function assertComboboxInput(
+  options: {
+    attributes?: Record<string, string | null>
+    state: ComboboxState
+  },
+  input = getComboboxInput()
+) {
+  try {
+    if (input === null) return expect(input).not.toBe(null)
+
+    // Ensure combobox input has these properties
+    expect(input).toHaveAttribute('id')
+
+    switch (options.state) {
+      case ComboboxState.Visible:
+        expect(input).toHaveAttribute('aria-controls')
+        expect(input).toHaveAttribute('aria-expanded', 'true')
+        break
+
+      case ComboboxState.InvisibleHidden:
+        expect(input).toHaveAttribute('aria-controls')
+        if (input.hasAttribute('disabled')) {
+          expect(input).not.toHaveAttribute('aria-expanded')
+        } else {
+          expect(input).toHaveAttribute('aria-expanded', 'false')
+        }
+        break
+
+      case ComboboxState.InvisibleUnmounted:
+        expect(input).not.toHaveAttribute('aria-controls')
+        if (input.hasAttribute('disabled')) {
+          expect(input).not.toHaveAttribute('aria-expanded')
+        } else {
+          expect(input).toHaveAttribute('aria-expanded', 'false')
+        }
+        break
+
+      default:
+        assertNever(options.state)
+    }
+
+    // Ensure combobox input has the following attributes
+    for (let attributeName in options.attributes) {
+      expect(input).toHaveAttribute(attributeName, options.attributes[attributeName])
+    }
+  } catch (err) {
+    if (err instanceof Error) Error.captureStackTrace(err, assertComboboxInput)
+    throw err
+  }
+}
+
 export function assertComboboxList(
   options: {
     attributes?: Record<string, string | null>
diff --git a/packages/@headlessui-vue/CHANGELOG.md b/packages/@headlessui-vue/CHANGELOG.md
index 3a84ef66f..3e0c20f31 100644
--- a/packages/@headlessui-vue/CHANGELOG.md
+++ b/packages/@headlessui-vue/CHANGELOG.md
@@ -20,6 +20,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Only render the `Dialog` on the client ([#1566](https://github.com/tailwindlabs/headlessui/pull/1566))
 - Improve Combobox input cursor position ([#1574](https://github.com/tailwindlabs/headlessui/pull/1574))
 - Fix scrolling issue in `Tab` component when using arrow keys ([#1584](https://github.com/tailwindlabs/headlessui/pull/1584))
+- Fix missing `aria-expanded` for `ComboboxInput` component ([#1605](https://github.com/tailwindlabs/headlessui/pull/1605))
 
 ## [1.6.4] - 2022-05-29
 
diff --git a/packages/@headlessui-vue/src/components/combobox/combobox.test.ts b/packages/@headlessui-vue/src/components/combobox/combobox.test.ts
index a21a230e9..77c9eb3b3 100644
--- a/packages/@headlessui-vue/src/components/combobox/combobox.test.ts
+++ b/packages/@headlessui-vue/src/components/combobox/combobox.test.ts
@@ -45,6 +45,7 @@ import {
   assertCombobox,
   ComboboxMode,
   assertNotActiveComboboxOption,
+  assertComboboxInput,
 } from '../../test-utils/accessibility-assertions'
 import { html } from '../../test-utils/html'
 import { useOpenClosedProvider, State, useOpenClosed } from '../../internal/open-closed'
@@ -332,8 +333,11 @@ describe('Rendering', () => {
         // TODO: Rendering Example directly reveals a vue bug — I think it's been fixed for a while but I can't find the commit
         renderTemplate(Example)
 
+        assertComboboxInput({ state: ComboboxState.InvisibleUnmounted })
+
         await click(getComboboxButton())
 
+        assertComboboxInput({ state: ComboboxState.Visible })
         assertComboboxList({ state: ComboboxState.Visible })
 
         await click(getComboboxOptions()[1])
diff --git a/packages/@headlessui-vue/src/components/combobox/combobox.ts b/packages/@headlessui-vue/src/components/combobox/combobox.ts
index 43f66f71c..401ca63a4 100644
--- a/packages/@headlessui-vue/src/components/combobox/combobox.ts
+++ b/packages/@headlessui-vue/src/components/combobox/combobox.ts
@@ -738,7 +738,9 @@ export let ComboboxInput = defineComponent({
       let slot = { open: api.comboboxState.value === ComboboxStates.Open }
       let ourProps = {
         'aria-controls': api.optionsRef.value?.id,
-        'aria-expanded': api.disabled ? undefined : api.comboboxState.value === ComboboxStates.Open,
+        'aria-expanded': api.disabled.value
+          ? undefined
+          : api.comboboxState.value === ComboboxStates.Open,
         'aria-activedescendant':
           api.activeOptionIndex.value === null
             ? undefined
diff --git a/packages/@headlessui-vue/src/test-utils/accessibility-assertions.ts b/packages/@headlessui-vue/src/test-utils/accessibility-assertions.ts
index 6eba1d4c1..37db4db69 100644
--- a/packages/@headlessui-vue/src/test-utils/accessibility-assertions.ts
+++ b/packages/@headlessui-vue/src/test-utils/accessibility-assertions.ts
@@ -330,6 +330,57 @@ export function assertCombobox(
   }
 }
 
+export function assertComboboxInput(
+  options: {
+    attributes?: Record<string, string | null>
+    state: ComboboxState
+  },
+  input = getComboboxInput()
+) {
+  try {
+    if (input === null) return expect(input).not.toBe(null)
+
+    // Ensure combobox input has these properties
+    expect(input).toHaveAttribute('id')
+
+    switch (options.state) {
+      case ComboboxState.Visible:
+        expect(input).toHaveAttribute('aria-controls')
+        expect(input).toHaveAttribute('aria-expanded', 'true')
+        break
+
+      case ComboboxState.InvisibleHidden:
+        expect(input).toHaveAttribute('aria-controls')
+        if (input.hasAttribute('disabled')) {
+          expect(input).not.toHaveAttribute('aria-expanded')
+        } else {
+          expect(input).toHaveAttribute('aria-expanded', 'false')
+        }
+        break
+
+      case ComboboxState.InvisibleUnmounted:
+        expect(input).not.toHaveAttribute('aria-controls')
+        if (input.hasAttribute('disabled')) {
+          expect(input).not.toHaveAttribute('aria-expanded')
+        } else {
+          expect(input).toHaveAttribute('aria-expanded', 'false')
+        }
+        break
+
+      default:
+        assertNever(options.state)
+    }
+
+    // Ensure combobox input has the following attributes
+    for (let attributeName in options.attributes) {
+      expect(input).toHaveAttribute(attributeName, options.attributes[attributeName])
+    }
+  } catch (err) {
+    if (err instanceof Error) Error.captureStackTrace(err, assertComboboxInput)
+    throw err
+  }
+}
+
 export function assertComboboxList(
   options: {
     attributes?: Record<string, string | null>