diff --git a/packages/@headlessui-react/src/components/listbox/listbox-machine.ts b/packages/@headlessui-react/src/components/listbox/listbox-machine.ts
index fa91da11e..d3f3034b7 100644
--- a/packages/@headlessui-react/src/components/listbox/listbox-machine.ts
+++ b/packages/@headlessui-react/src/components/listbox/listbox-machine.ts
@@ -390,28 +390,14 @@ let reducers: {
     }
   },
   [ActionTypes.UnregisterOptions]: (state, action) => {
-    let options = state.options
-
-    let idxs = []
     let ids = new Set(action.options)
-    for (let [idx, option] of options.entries()) {
-      if (ids.has(option.id)) {
-        idxs.push(idx)
-        ids.delete(option.id)
-        if (ids.size === 0) break
-      }
-    }
-
-    if (idxs.length > 0) {
-      options = options.slice()
-      for (let idx of idxs.reverse()) {
-        options.splice(idx, 1)
-      }
-    }
+    let adjustedState = adjustOrderedState(state, (options) => {
+      return options.filter((option) => !ids.has(option.id))
+    })
 
     return {
       ...state,
-      options,
+      ...adjustedState,
       activationTrigger: ActivationTrigger.Other,
     }
   },
@@ -590,7 +576,9 @@ export class ListboxMachine<T> extends Machine<State<T>, Actions<T>> {
 
     selectActiveOption: () => {
       if (this.state.activeOptionIndex !== null) {
-        let { dataRef } = this.state.options[this.state.activeOptionIndex]
+        let activeOption = this.state.options[this.state.activeOptionIndex]
+        if (!activeOption) return
+        let { dataRef } = activeOption
         this.actions.selectOption(dataRef.current.value)
       } else if (this.state.dataRef.current.mode === ValueMode.Single) {
         this.actions.closeListbox()
diff --git a/packages/@headlessui-react/src/components/listbox/listbox.test.tsx b/packages/@headlessui-react/src/components/listbox/listbox.test.tsx
index 15b2d7575..58c9bc898 100644
--- a/packages/@headlessui-react/src/components/listbox/listbox.test.tsx
+++ b/packages/@headlessui-react/src/components/listbox/listbox.test.tsx
@@ -4705,3 +4705,78 @@ describe('transitions', () => {
     })
   )
 })
+
+describe('Dynamic option removal', () => {
+  it(
+    'should not crash when the active option is removed',
+    suppressConsoleLogs(async () => {
+      function Example({ hide = false }) {
+        return (
+          <Listbox value={undefined} onChange={(x) => console.log(x)}>
+            <Listbox.Button>Trigger</Listbox.Button>
+            <Listbox.Options>
+              <Listbox.Option value="a">alice</Listbox.Option>
+              {!hide && <Listbox.Option value="b">bob</Listbox.Option>}
+              {!hide && <Listbox.Option value="c">charlie</Listbox.Option>}
+            </Listbox.Options>
+          </Listbox>
+        )
+      }
+
+      let { rerender } = render(<Example />)
+
+      // Open the listbox
+      await click(getListboxButton())
+      assertListbox({ state: ListboxState.Visible })
+
+      // Navigate to the last option
+      await press(Keys.End)
+      let options = getListboxOptions()
+      assertActiveListboxOption(options[2])
+
+      // Remove options while the listbox is open
+      rerender(<Example hide={true} />)
+
+      // Press Enter — should not crash, should close the listbox gracefully
+      await press(Keys.Enter)
+      assertListbox({ state: ListboxState.InvisibleUnmounted })
+    })
+  )
+
+  it(
+    'should adjust activeOptionIndex when options before the active option are removed',
+    suppressConsoleLogs(async () => {
+      function Example({ hide = false }) {
+        return (
+          <Listbox value={undefined} onChange={(x) => console.log(x)}>
+            <Listbox.Button>Trigger</Listbox.Button>
+            <Listbox.Options>
+              {!hide && <Listbox.Option value="a">alice</Listbox.Option>}
+              <Listbox.Option value="b">bob</Listbox.Option>
+              <Listbox.Option value="c">charlie</Listbox.Option>
+            </Listbox.Options>
+          </Listbox>
+        )
+      }
+
+      let { rerender } = render(<Example />)
+
+      // Open the listbox
+      await click(getListboxButton())
+      assertListbox({ state: ListboxState.Visible })
+
+      // Navigate to the last option ("charlie")
+      await press(Keys.End)
+      let options = getListboxOptions()
+      assertActiveListboxOption(options[2])
+
+      // Remove the first option ("alice") while "charlie" is active
+      rerender(<Example hide={true} />)
+
+      // "charlie" should still be the active option (now at index 1)
+      options = getListboxOptions()
+      expect(options).toHaveLength(2)
+      assertActiveListboxOption(options[1])
+    })
+  )
+})
diff --git a/packages/@headlessui-react/src/components/menu/menu-machine.ts b/packages/@headlessui-react/src/components/menu/menu-machine.ts
index ac363af1d..db8c10943 100644
--- a/packages/@headlessui-react/src/components/menu/menu-machine.ts
+++ b/packages/@headlessui-react/src/components/menu/menu-machine.ts
@@ -305,28 +305,14 @@ let reducers: {
     }
   },
   [ActionTypes.UnregisterItems]: (state, action) => {
-    let items = state.items
-
-    let idxs = []
     let ids = new Set(action.items)
-    for (let [idx, item] of items.entries()) {
-      if (ids.has(item.id)) {
-        idxs.push(idx)
-        ids.delete(item.id)
-        if (ids.size === 0) break
-      }
-    }
-
-    if (idxs.length > 0) {
-      items = items.slice()
-      for (let idx of idxs.reverse()) {
-        items.splice(idx, 1)
-      }
-    }
+    let adjustedState = adjustOrderedState(state, (items) => {
+      return items.filter((item) => !ids.has(item.id))
+    })
 
     return {
       ...state,
-      items,
+      ...adjustedState,
       activationTrigger: ActivationTrigger.Other,
     }
   },
diff --git a/packages/@headlessui-react/src/components/menu/menu.test.tsx b/packages/@headlessui-react/src/components/menu/menu.test.tsx
index 14a2d3109..9ccd1434c 100644
--- a/packages/@headlessui-react/src/components/menu/menu.test.tsx
+++ b/packages/@headlessui-react/src/components/menu/menu.test.tsx
@@ -3604,3 +3604,78 @@ describe('transitions', () => {
     })
   )
 })
+
+describe('Dynamic item removal', () => {
+  it(
+    'should not crash when the active item is removed',
+    suppressConsoleLogs(async () => {
+      function Example({ hide = false }) {
+        return (
+          <Menu>
+            <Menu.Button>Trigger</Menu.Button>
+            <Menu.Items>
+              <Menu.Item as="button">alice</Menu.Item>
+              {!hide && <Menu.Item as="button">bob</Menu.Item>}
+              {!hide && <Menu.Item as="button">charlie</Menu.Item>}
+            </Menu.Items>
+          </Menu>
+        )
+      }
+
+      let { rerender } = render(<Example />)
+
+      // Open the menu
+      await click(getMenuButton())
+      assertMenu({ state: MenuState.Visible })
+
+      // Navigate to the last item
+      await press(Keys.End)
+      let items = getMenuItems()
+      assertMenuLinkedWithMenuItem(items[2])
+
+      // Remove items while the menu is open
+      rerender(<Example hide={true} />)
+
+      // Press Enter — should not crash, should close the menu gracefully
+      await press(Keys.Enter)
+      assertMenu({ state: MenuState.InvisibleUnmounted })
+    })
+  )
+
+  it(
+    'should adjust activeItemIndex when items before the active item are removed',
+    suppressConsoleLogs(async () => {
+      function Example({ hide = false }) {
+        return (
+          <Menu>
+            <Menu.Button>Trigger</Menu.Button>
+            <Menu.Items>
+              {!hide && <Menu.Item as="button">alice</Menu.Item>}
+              <Menu.Item as="button">bob</Menu.Item>
+              <Menu.Item as="button">charlie</Menu.Item>
+            </Menu.Items>
+          </Menu>
+        )
+      }
+
+      let { rerender } = render(<Example />)
+
+      // Open the menu
+      await click(getMenuButton())
+      assertMenu({ state: MenuState.Visible })
+
+      // Navigate to the last item ("charlie")
+      await press(Keys.End)
+      let items = getMenuItems()
+      assertMenuLinkedWithMenuItem(items[2])
+
+      // Remove the first item ("alice") while "charlie" is active
+      rerender(<Example hide={true} />)
+
+      // "charlie" should still be the active item (now at index 1)
+      items = getMenuItems()
+      expect(items).toHaveLength(2)
+      assertMenuLinkedWithMenuItem(items[1])
+    })
+  )
+})
diff --git a/packages/@headlessui-react/src/components/menu/menu.tsx b/packages/@headlessui-react/src/components/menu/menu.tsx
index 635632072..a14f25186 100644
--- a/packages/@headlessui-react/src/components/menu/menu.tsx
+++ b/packages/@headlessui-react/src/components/menu/menu.tsx
@@ -473,7 +473,9 @@ function ItemsFn<TTag extends ElementType = typeof DEFAULT_ITEMS_TAG>(
         event.preventDefault()
         event.stopPropagation()
         if (machine.state.activeItemIndex !== null) {
-          let { dataRef } = machine.state.items[machine.state.activeItemIndex]
+          let activeItem = machine.state.items[machine.state.activeItemIndex]
+          if (!activeItem) break
+          let { dataRef } = activeItem
           dataRef.current?.domRef.current?.click()
         }
         machine.send({ type: ActionTypes.CloseMenu })