diff --git a/src/jsc/bindings/JSMockFunction.cpp b/src/jsc/bindings/JSMockFunction.cpp
index 1c1c7fe70f6..c2239b49da1 100644
--- a/src/jsc/bindings/JSMockFunction.cpp
+++ b/src/jsc/bindings/JSMockFunction.cpp
@@ -86,6 +86,7 @@ inline To tryJSDynamicCast(JSC::WriteBarrier<WriteBarrierT>& from)
 }
 
 JSC_DECLARE_HOST_FUNCTION(jsMockFunctionCall);
+JSC_DECLARE_HOST_FUNCTION(jsMockFunctionConstruct);
 JSC_DECLARE_CUSTOM_GETTER(jsMockFunctionGetter_protoImpl);
 JSC_DECLARE_CUSTOM_GETTER(jsMockFunctionGetter_mock);
 JSC_DECLARE_HOST_FUNCTION(jsMockFunctionGetter_mockGetLastCall);
@@ -462,7 +463,7 @@ class JSMockFunction : public JSC::InternalFunction {
     }
 
     JSMockFunction(JSC::VM& vm, JSC::Structure* structure, CallbackKind wrapKind)
-        : Base(vm, structure, jsMockFunctionCall, jsMockFunctionCall)
+        : Base(vm, structure, jsMockFunctionCall, jsMockFunctionConstruct)
     {
         initMock();
     }
@@ -981,6 +982,34 @@ JSC_DEFINE_HOST_FUNCTION(jsMockFunctionCall, (JSGlobalObject * lexicalGlobalObje
     return JSValue::encode(jsUndefined());
 }
 
+// A native constructor must return an object, but a mock implementation can produce any value.
+// Follow ordinary [[Construct]] semantics: if the implementation does not return an object,
+// return a fresh object created from newTarget's prototype instead.
+JSC_DEFINE_HOST_FUNCTION(jsMockFunctionConstruct, (JSGlobalObject * globalObject, CallFrame* callframe))
+{
+    auto& vm = JSC::getVM(globalObject);
+    auto scope = DECLARE_THROW_SCOPE(vm);
+
+    JSValue returnValue = JSValue::decode(jsMockFunctionCall(globalObject, callframe));
+    RETURN_IF_EXCEPTION(scope, {});
+
+    if (returnValue && returnValue.isObject()) {
+        return JSValue::encode(returnValue);
+    }
+
+    JSValue newTarget = callframe->newTarget();
+    JSValue prototype = jsUndefined();
+    if (newTarget && newTarget.isObject()) {
+        prototype = asObject(newTarget)->get(globalObject, vm.propertyNames->prototype);
+        RETURN_IF_EXCEPTION(scope, {});
+    }
+
+    JSObject* thisObject = prototype.isObject()
+        ? JSC::constructEmptyObject(globalObject, asObject(prototype))
+        : JSC::constructEmptyObject(globalObject);
+    RELEASE_AND_RETURN(scope, JSValue::encode(thisObject));
+}
+
 void JSMockFunctionPrototype::finishCreation(JSC::VM& vm, JSC::JSGlobalObject* globalObject)
 {
     Base::finishCreation(vm);
diff --git a/test/js/bun/test/mock-fn.test.js b/test/js/bun/test/mock-fn.test.js
index 7f6a244d980..6715d02d918 100644
--- a/test/js/bun/test/mock-fn.test.js
+++ b/test/js/bun/test/mock-fn.test.js
@@ -794,6 +794,22 @@ describe("mock()", () => {
 
     expect(bar()()).toBe(true);
   });
+
+  test("constructing a mock returns an object even when the implementation returns a primitive", () => {
+    const fn = jest.fn();
+    expect(typeof new fn()).toBe("object");
+    expect(typeof Reflect.construct(fn, [])).toBe("object");
+
+    const returnsPrimitive = jest.fn().mockReturnValue(42);
+    expect(typeof new returnsPrimitive()).toBe("object");
+    expect(typeof Reflect.construct(returnsPrimitive, [])).toBe("object");
+    expect(returnsPrimitive).toHaveBeenCalledTimes(2);
+
+    const instance = { a: 1 };
+    const returnsObject = jest.fn(() => instance);
+    expect(new returnsObject()).toBe(instance);
+    expect(Reflect.construct(returnsObject, [])).toBe(instance);
+  });
 });
 
 describe("spyOn", () => {
@@ -1011,6 +1027,14 @@ describe("spyOn", () => {
       expect(arr[14]()).toBe(456);
       expect(fn).not.toHaveBeenCalled();
     });
+
+    test("constructing a spy on a missing property does not crash", () => {
+      const target = {};
+      const spy = spyOn(target, "doesNotExist");
+      expect(typeof Reflect.construct(spy, [])).toBe("object");
+      expect(spy).toHaveBeenCalledTimes(1);
+      spy.mockRestore();
+    });
   }
 
   // spyOn does not work with getters/setters yet.