diff --git a/src/runtime/webcore/Blob.zig b/src/runtime/webcore/Blob.zig
index 6cf5c0475545..62fbf8c8f0e5 100644
--- a/src/runtime/webcore/Blob.zig
+++ b/src/runtime/webcore/Blob.zig
@@ -2975,7 +2975,11 @@ pub fn getWriter(
 
     if (arguments.len > 0 and arguments.ptr[0].isObject()) {
         stream_start = try jsc.WebCore.streams.Start.fromJSWithTag(globalThis, arguments[0], .FileSink);
-        stream_start.FileSink.input_path = input_path;
+        if (stream_start == .FileSink) {
+            stream_start.FileSink.input_path = input_path;
+        } else {
+            stream_start = .{ .FileSink = .{ .input_path = input_path } };
+        }
     }
 
     switch (sink.start(stream_start)) {
diff --git a/test/js/bun/util/filesink.test.ts b/test/js/bun/util/filesink.test.ts
index 736e5b085731..0203d069fcac 100644
--- a/test/js/bun/util/filesink.test.ts
+++ b/test/js/bun/util/filesink.test.ts
@@ -268,3 +268,17 @@ it.skipIf(!isPosix)("does not leak native FileSink when a pending write fails (E
   // more than that indicates a native leak.
   expect(fileSinkInternals.liveCount()).toBeLessThanOrEqual(baseline + 1);
 });
+
+describe("Bun.file().writer() with invalid options", () => {
+  it.each([
+    ["non-string path", { path: 123 }],
+    ["non-integer fd", { fd: "notanint" }],
+    ["arbitrary object", Bun],
+  ])("does not crash with %s", async (_, options) => {
+    const path = join(tmpdirSync(), "filesink-invalid-options.txt");
+    const writer = Bun.file(path).writer(options as any);
+    writer.write("hello");
+    await writer.end();
+    expect(await Bun.file(path).text()).toBe("hello");
+  });
+});