2 files changed, 14 insertions, 5 deletions
diff --git a/multipart/formfile.ts b/multipart/formfile.ts
index 592f4e529..a0e721a15 100644
--- a/multipart/formfile.ts
+++ b/multipart/formfile.ts
@@ -1,4 +1,5 @@
 // Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+import { hasOwnProperty } from "../util/has_own_property.ts";
 
 /** FormFile object */
 export interface FormFile {
@@ -19,9 +20,5 @@ export interface FormFile {
 /** Type guard for FormFile */
 // eslint-disable-next-line @typescript-eslint/no-explicit-any
 export function isFormFile(x: any): x is FormFile {
-  return (
-    typeof x === "object" &&
-    x.hasOwnProperty("filename") &&
-    x.hasOwnProperty("type")
-  );
+  return hasOwnProperty(x, "filename") && hasOwnProperty(x, "type");
 }
diff --git a/multipart/formfile_test.ts b/multipart/formfile_test.ts
index 63509fc9d..52dd3addd 100644
--- a/multipart/formfile_test.ts
+++ b/multipart/formfile_test.ts
@@ -18,3 +18,15 @@ test(function multipartIsFormFile(): void {
     false
   );
 });
+
+test(function isFormFileShouldNotThrow(): void {
+  assertEquals(
+    isFormFile({
+      filename: "foo",
+      type: "application/json",
+      hasOwnProperty: "bar"
+    }),
+    true
+  );
+  assertEquals(isFormFile(Object.create(null)), false);
+});