diff --git a/expect/_unstable_asserts_compability_test.ts b/expect/_unstable_asserts_compability_test.ts
new file mode 100644
index 000000000000..1f407499f47c
--- /dev/null
+++ b/expect/_unstable_asserts_compability_test.ts
@@ -0,0 +1,51 @@
+// Copyright 2018-2024 the Deno authors. All rights reserved. MIT license.
+
+import {
+  assertSpyCall,
+  assertSpyCallArg,
+  assertSpyCallArgs,
+  assertSpyCallAsync,
+  assertSpyCalls,
+  spy,
+} from "@std/testing/unstable-mock";
+import { expect } from "./unstable_expect.ts";
+import { fn } from "./unstable_fn.ts";
+
+Deno.test("@std/expect/fn should be compatible with @std/testing/mock asserts", async () => {
+  const mockFn = fn((a: number, b: number) => a + b);
+  mockFn(1, 1);
+  mockFn(1, 2);
+
+  assertSpyCalls(mockFn, 2);
+  assertSpyCall(mockFn, 0, { args: [1, 1], returned: 2 });
+  assertSpyCallArgs(mockFn, 1, [1, 2]);
+  assertSpyCallArg(mockFn, 0, 0, 1);
+
+  const mockAsyncFn = fn((a: number, b: number) => Promise.resolve(a + b));
+  await mockAsyncFn(1, 1);
+  await assertSpyCallAsync(mockAsyncFn, 0, {
+    args: [1, 1],
+    returned: 2,
+  });
+});
+
+Deno.test("@std/testing/mock should be compatible with @std/expect", () => {
+  const sum = (a: number, b: number) => a + b;
+
+  const value = { sum };
+  const methodFn = spy(value, "sum");
+  value.sum(1, 1);
+  expect(methodFn).toHaveBeenCalledWith(1, 1);
+  expect(methodFn).toHaveReturnedWith(2);
+
+  const spyFn = spy(sum);
+  spyFn(1, 1);
+  spyFn(1, 2);
+  expect(spyFn).toHaveBeenCalledTimes(2);
+  expect(spyFn).toHaveBeenLastCalledWith(1, 2);
+
+  class A {}
+  const constructorFn = spy(A);
+  expect(new constructorFn()).toBeInstanceOf(A);
+  expect(constructorFn).toHaveReturnedWith(expect.any(A));
+});
diff --git a/expect/_unstable_mock_instance.ts b/expect/_unstable_mock_instance.ts
index ee1eac1acca1..a41a358accf1 100644
--- a/expect/_unstable_mock_instance.ts
+++ b/expect/_unstable_mock_instance.ts
@@ -60,7 +60,7 @@ export function createMockInstance<
         args,
         timestamp: Date.now(),
         result: "returned",
-        returned,
+        returned: returned as never,
       });
       return returned;
     } catch (error) {
diff --git a/expect/_unstable_mock_utils.ts b/expect/_unstable_mock_utils.ts
index 862b0bf7617d..e56dd2ffea41 100644
--- a/expect/_unstable_mock_utils.ts
+++ b/expect/_unstable_mock_utils.ts
@@ -5,13 +5,9 @@ import { MOCK_SYMBOL, type MockCall } from "@std/internal/unstable_mock";
 export { isMockFunction, MOCK_SYMBOL } from "@std/internal/unstable_mock";
 
 export type ExpectMockCall<Args extends unknown[], Return> =
-  & Omit<
-    MockCall<Args, Return>,
-    "returned"
-  >
+  & MockCall<Args, Return>
   & {
     timestamp: number;
-    returned?: Return | undefined;
   };
 export interface ExpectMockInternals<Args extends unknown[], Return> {
   readonly calls: ExpectMockCall<Args, Return>[];