diff --git a/CHANGELOG.md b/CHANGELOG.md
index c00a7b0..3887b0b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -13,6 +13,9 @@ against this file to see what a re-vendor would bring.
   the README example should update the URL in their own notice.
 - The README's Keys section no longer links to a decision record in that
   private repository.
+- `report(name, null)` from untyped code now sends the event as if no
+  options were given. It used to drop the event and log a misleading
+  "could not serialize" line to `debug`.
 
 ## 0.4.0 — 2026-10-03
 
diff --git a/tests/trace-client.test.ts b/tests/trace-client.test.ts
index d8f8404..d8a1254 100644
--- a/tests/trace-client.test.ts
+++ b/tests/trace-client.test.ts
@@ -10,6 +10,7 @@ import { join } from "node:path";
 
 import * as clientModule from "../trace-client.ts";
 import { TraceClient, TRACE_CLIENT_VERSION, isBot, pagePath } from "../trace-client.ts";
+import type { ReportOptions } from "../trace-client.ts";
 
 const { REASON_CONFIG, REASON_ENVIRONMENT, REASON_NO_KEY } = TraceClient;
 const environmentOptsOut = (env?: Record<string, string | undefined>) => TraceClient.environmentOptsOut(env);
@@ -294,6 +295,33 @@ describe("TraceClient", () => {
     await client.close();
   });
 
+  it("sends the event when untyped code passes null or a non-object as options", async () => {
+    const client = new TraceClient(baseUrl, "MyGame", { version: "1.2.3", key: "k", debug });
+    for (const options of [null, 42, "loose"]) {
+      await client.report("startup", options as unknown as ReportOptions);
+    }
+    assert.equal(capture.requests.length, 3, "no options was meant, so nothing is dropped");
+    for (const request of capture.requests) {
+      assert.deepEqual(JSON.parse(request.body), { application: "MyGame", name: "startup", tags: { version: "1.2.3" } });
+    }
+    await client.close();
+    assert.deepEqual(log, [], "a missing options object is not a serialize failure");
+  });
+
+  it("does not throw when reading the options throws", async () => {
+    const client = new TraceClient(baseUrl, "MyGame", { version: "1.2.3", key: "k", debug });
+    const hostile = {
+      get value(): number {
+        throw new Error("boom");
+      },
+    };
+    await client.report("startup", hostile);
+    await client.close();
+    assert.deepEqual(capture.requests, []);
+    assert.equal(log.length, 1, "the drop goes to debug instead of escaping report()");
+    assert.match(log[0], /could not serialize startup/);
+  });
+
   it("rejects a missing baseUrl or application at construction", () => {
     assert.throws(() => new TraceClient("", "MyGame", { version: "1.2.3" }));
     assert.throws(() => new TraceClient("  ", "MyGame", { version: "1.2.3" }));
diff --git a/trace-client.ts b/trace-client.ts
index e39c199..b0424a0 100644
--- a/trace-client.ts
+++ b/trace-client.ts
@@ -353,7 +353,9 @@ export class TraceClient {
     }
     let body: string;
     try {
-      body = serialize(this.application, name, options.value, withInstall(withVersion(options.tags, this.version), this.install));
+      // A null (or other non-object) options from untyped code means "no options".
+      const { value, tags } = options !== null && typeof options === "object" ? options : ({} as ReportOptions);
+      body = serialize(this.application, name, value, withInstall(withVersion(tags, this.version), this.install));
     } catch (failure) {
       this.log(`could not serialize ${name}: ${describe(failure)}`);
       return Promise.resolve();