diff --git a/src/app/page.tsx b/src/app/page.tsx
index f8d06d2..cff189b 100644
--- a/src/app/page.tsx
+++ b/src/app/page.tsx
@@ -16,6 +16,7 @@ import { getFileName } from '../fs'
 import TitleText from '../components/TitleText'
 import { pluralize } from '../utils/pluralize'
 import TermsAcceptance from '../components/TermsAcceptance'
+import AddFilesButton from '../components/AddFilesButton'
 
 function PageWrapper({ children }: { children: React.ReactNode }): JSX.Element {
   return (
@@ -59,6 +60,7 @@ function ConfirmUploadState({
   onCancel,
   onStart,
   onRemoveFile,
+  onAddFiles,
 }: {
   uploadedFiles: UploadedFile[]
   password: string
@@ -66,6 +68,7 @@ function ConfirmUploadState({
   onCancel: () => void
   onStart: () => void
   onRemoveFile: (index: number) => void
+  onAddFiles: (files: UploadedFile[]) => void
 }): JSX.Element {
   const fileListData = useUploaderFileListData(uploadedFiles)
   return (
@@ -75,6 +78,9 @@ function ConfirmUploadState({
         {pluralize(uploadedFiles.length, 'file', 'files')}.
       </TitleText>
       <UploadFileList files={fileListData} onRemove={onRemoveFile} />
+      <div className="flex justify-end w-full">
+        <AddFilesButton onAdd={onAddFiles} />
+      </div>
       <PasswordField value={password} onChange={onChangePassword} />
       <div className="flex space-x-4">
         <CancelButton onClick={onCancel} />
@@ -137,6 +143,10 @@ export default function UploadPage(): JSX.Element {
     setUploadedFiles((fs) => fs.filter((_, i) => i !== index))
   }, [])
 
+  const handleAddFiles = useCallback((files: UploadedFile[]) => {
+    setUploadedFiles((fs) => [...fs, ...files])
+  }, [])
+
   if (!uploadedFiles.length) {
     return <InitialState onDrop={handleDrop} />
   }
@@ -150,6 +160,7 @@ export default function UploadPage(): JSX.Element {
         onCancel={handleCancel}
         onStart={handleStart}
         onRemoveFile={handleRemoveFile}
+        onAddFiles={handleAddFiles}
       />
     )
   }
diff --git a/src/components/AddFilesButton.tsx b/src/components/AddFilesButton.tsx
new file mode 100644
index 0000000..1a11526
--- /dev/null
+++ b/src/components/AddFilesButton.tsx
@@ -0,0 +1,45 @@
+import React, { useRef, useCallback, JSX } from 'react'
+import { UploadedFile } from '../types'
+
+export default function AddFilesButton({
+  onAdd,
+}: {
+  onAdd: (files: UploadedFile[]) => void
+}): JSX.Element {
+  const fileInputRef = useRef<HTMLInputElement>(null)
+
+  const handleClick = useCallback(() => {
+    fileInputRef.current?.click()
+  }, [])
+
+  const handleChange = useCallback(
+    (e: React.ChangeEvent<HTMLInputElement>) => {
+      if (e.target.files) {
+        onAdd(Array.from(e.target.files) as UploadedFile[])
+        e.target.value = ''
+      }
+    },
+    [onAdd],
+  )
+
+  return (
+    <>
+      <input
+        id="add-files-input"
+        type="file"
+        ref={fileInputRef}
+        className="hidden"
+        multiple
+        onChange={handleChange}
+      />
+      <button
+        id="add-files-button"
+        type="button"
+        onClick={handleClick}
+        className="block cursor-pointer relative py-3 px-6 text-base font-bold text-stone-700 dark:text-stone-200 bg-white dark:bg-stone-800 border-2 border-stone-700 dark:border-stone-700 rounded-lg transition-all duration-300 ease-in-out outline-none hover:shadow-md active:shadow-inner focus:shadow-outline"
+      >
+        Add more files
+      </button>
+    </>
+  )
+}
diff --git a/tests/e2e/add-files.test.ts b/tests/e2e/add-files.test.ts
new file mode 100644
index 0000000..17da139
--- /dev/null
+++ b/tests/e2e/add-files.test.ts
@@ -0,0 +1,17 @@
+/// <reference types="@playwright/test" />
+import { test, expect } from '@playwright/test'
+import { createTestFile, uploadFile, addFile } from './helpers'
+
+test('user can add more files before starting upload', async ({ page }) => {
+  const file1 = createTestFile('first.txt', 'A')
+  const file2 = createTestFile('second.txt', 'B')
+
+  await uploadFile(page, file1)
+
+  // Add another file using the add files button
+  await addFile(page, file2)
+
+  // Both files should be listed
+  await expect(page.getByText(file1.name)).toBeVisible()
+  await expect(page.getByText(file2.name)).toBeVisible()
+})
diff --git a/tests/e2e/helpers.ts b/tests/e2e/helpers.ts
index 48ea67d..a47b7d3 100644
--- a/tests/e2e/helpers.ts
+++ b/tests/e2e/helpers.ts
@@ -66,6 +66,33 @@ export async function uploadFile(
   )
 }
 
+export async function addFile(
+  page: Page,
+  testFile: TestFile,
+): Promise<void> {
+  await page.evaluate(
+    ({ testContent, testFileName }) => {
+      const input = document.querySelector(
+        '#add-files-input',
+      ) as HTMLInputElement
+      if (input) {
+        const file = new File([testContent], testFileName, {
+          type: 'text/plain',
+        })
+        const dataTransfer = new DataTransfer()
+        dataTransfer.items.add(file)
+        input.files = dataTransfer.files
+
+        const event = new Event('change', { bubbles: true })
+        input.dispatchEvent(event)
+      }
+    },
+    { testContent: testFile.content, testFileName: testFile.name },
+  )
+
+  await expect(page.getByText(testFile.name)).toBeVisible({ timeout: 5000 })
+}
+
 export async function startUpload(page: Page): Promise<string> {
   // Start sharing
   await page.locator('#start-button').click()