diff --git a/client/mock/mock.go b/client/mock/mock.go
index e9022c71..6ee8f1f8 100644
--- a/client/mock/mock.go
+++ b/client/mock/mock.go
@@ -83,7 +83,11 @@ func (m *MockClient) Call(ctx context.Context, req client.Request, rsp interface
 		}
 		response := r.Response
 		if t := reflect.TypeOf(r.Response); t.Kind() == reflect.Func {
-			response = reflect.ValueOf(r.Response).Call([]reflect.Value{})[0].Interface()
+			var request []reflect.Value
+			if t.NumIn() == 1 {
+				request = append(request, reflect.ValueOf(req.Body()))
+			}
+			response = reflect.ValueOf(r.Response).Call(request)[0].Interface()
 		}
 
 		v.Set(reflect.ValueOf(response))
diff --git a/client/mock/mock_test.go b/client/mock/mock_test.go
index 5dc5de1b..4f00f8a9 100644
--- a/client/mock/mock_test.go
+++ b/client/mock/mock_test.go
@@ -18,12 +18,18 @@ func TestClient(t *testing.T) {
 		{Endpoint: "Foo.Fail", Error: errors.InternalServerError("go.mock", "failed")},
 		{Endpoint: "Foo.Func", Response: func() string { return "string" }},
 		{Endpoint: "Foo.FuncStruct", Response: func() *TestResponse { return &TestResponse{Param: "aparam"} }},
+		{Endpoint: "Foo.FuncWithReqBody", Response: func(req interface{}) string {
+			if req.(map[string]string)["foo"] == "bar" {
+				return "string"
+			}
+			return "wrong"
+		}},
 	}
 
 	c := NewClient(Response("go.mock", response))
 
 	for _, r := range response {
-		req := c.NewRequest("go.mock", r.Endpoint, map[string]interface{}{"foo": "bar"})
+		req := c.NewRequest("go.mock", r.Endpoint, map[string]string{"foo": "bar"})
 		var rsp interface{}
 
 		err := c.Call(context.TODO(), req, &rsp)
@@ -33,6 +39,20 @@ func TestClient(t *testing.T) {
 		}
 
 		t.Log(rsp)
+		if r.Endpoint == "Foo.FuncWithReqBody" {
+			req := c.NewRequest("go.mock", r.Endpoint, map[string]string{"foo": "wrong"})
+			var rsp interface{}
+
+			err := c.Call(context.TODO(), req, &rsp)
+
+			if err != r.Error {
+				t.Fatalf("Expecter error %v got %v", r.Error, err)
+			}
+			if rsp.(string) != "wrong" {
+				t.Fatalf("Expecter response 'wrong' got %v", rsp)
+			}
+			t.Log(rsp)
+		}
 	}
 
 }