diff --git a/src/uploads.ts b/src/uploads.ts
index a920351cd..8fd2154d4 100644
--- a/src/uploads.ts
+++ b/src/uploads.ts
@@ -107,8 +107,10 @@ export async function toFile(
   // If it's a promise, resolve it.
   value = await value;
 
-  // Use the file's options if there isn't one provided
-  options ??= isFileLike(value) ? { lastModified: value.lastModified, type: value.type } : {};
+  // If we've been given a `File` we don't need to do anything
+  if (isFileLike(value)) {
+    return value;
+  }
 
   if (isResponseLike(value)) {
     const blob = await value.blob();
@@ -126,7 +128,7 @@ export async function toFile(
 
   name ||= getName(value) ?? 'unknown_file';
 
-  if (!options.type) {
+  if (!options?.type) {
     const type = (bits[0] as any)?.type;
     if (typeof type === 'string') {
       options = { ...options, type };
diff --git a/tests/uploads.test.ts b/tests/uploads.test.ts
index b40856e29..b64b80285 100644
--- a/tests/uploads.test.ts
+++ b/tests/uploads.test.ts
@@ -54,4 +54,12 @@ describe('toFile', () => {
     const file = await toFile(input);
     expect(file.name).toEqual('uploads.test.ts');
   });
+
+  it('does not copy File objects', async () => {
+    const input = new File(['foo'], 'input.jsonl', { type: 'jsonl' });
+    const file = await toFile(input);
+    expect(file).toBe(input);
+    expect(file.name).toEqual('input.jsonl');
+    expect(file.type).toBe('jsonl');
+  });
 });