diff --git a/src/file.ts b/src/file.ts
index d7dc41a9f..e4438a7d8 100644
--- a/src/file.ts
+++ b/src/file.ts
@@ -361,7 +361,9 @@ export interface CopyOptions {
   contentType?: string;
   contentDisposition?: string;
   destinationKmsKeyName?: string;
-  metadata?: FileMetadata;
+  metadata?: {
+    [key: string]: string | boolean | number | null;
+  };
   predefinedAcl?: string;
   token?: string;
   userProject?: string;
diff --git a/test/file.ts b/test/file.ts
index d0cc0c2ba..bd95ad26d 100644
--- a/test/file.ts
+++ b/test/file.ts
@@ -545,12 +545,17 @@ describe('File', () => {
 
     it('should accept an options object', done => {
       const newFile = new File(BUCKET, 'name');
+      const METADATA = {
+        metadataKey: 'metadataValue',
+      };
       const options = {
         option: true,
+        metadata: METADATA,
       };
 
       file.request = (reqOpts: DecorateRequestOptions) => {
         assert.deepStrictEqual(reqOpts.json, options);
+        assert.strictEqual(reqOpts.json.metadata, METADATA);
         done();
       };