diff --git a/tests/camera2/CameraMultiStreamTests.cpp b/tests/camera2/CameraMultiStreamTests.cpp
index eb64db1..f4aeab7 100644
--- a/tests/camera2/CameraMultiStreamTests.cpp
+++ b/tests/camera2/CameraMultiStreamTests.cpp
@@ -334,7 +334,7 @@
             int height,
             const sp<CameraDeviceBase>& device,
             CameraStreamParams param = DEFAULT_STREAM_PARAMETERS,
-            sp<Surface> surface = NULL,
+            const sp<Surface>& surface = NULL,
             bool useCpuConsumer = true) {
         param.mFormat = MapAutoFormat(param.mFormat);
         return new CameraStream(width, height, device,
diff --git a/tests/camera2/camera2_utils.cpp b/tests/camera2/camera2_utils.cpp
index c63c32a..dab0ae9 100644
--- a/tests/camera2/camera2_utils.cpp
+++ b/tests/camera2/camera2_utils.cpp
@@ -176,7 +176,7 @@
 }
 
 status_t MetadataQueue::freeBuffers(List<camera_metadata_t*>::iterator start,
-                                    List<camera_metadata_t*>::iterator end) {
+                                    const List<camera_metadata_t*>::iterator& end) {
     while (start != end) {
         free_camera_metadata(*start);
         start = mStreamSlot.erase(start);
diff --git a/tests/camera2/camera2_utils.h b/tests/camera2/camera2_utils.h
index a01bae2..274ee76 100644
--- a/tests/camera2/camera2_utils.h
+++ b/tests/camera2/camera2_utils.h
@@ -65,7 +65,7 @@
 
   private:
     status_t freeBuffers(List<camera_metadata_t*>::iterator start,
-                         List<camera_metadata_t*>::iterator end);
+                         const List<camera_metadata_t*>::iterator& end);
 
     camera2_device_t *mDevice;
 
diff --git a/tests/input/evdev/InputHub_test.cpp b/tests/input/evdev/InputHub_test.cpp
index 64671ff..3d62152 100644
--- a/tests/input/evdev/InputHub_test.cpp
+++ b/tests/input/evdev/InputHub_test.cpp
@@ -50,9 +50,9 @@
         mInputCb(kNoopInputCb), mDeviceAddedCb(kNoopDeviceCb), mDeviceRemovedCb(kNoopDeviceCb) {}
     virtual ~TestInputCallback() = default;
 
-    void setInputCallback(InputCbFunc cb) { mInputCb = cb; }
-    void setDeviceAddedCallback(DeviceCbFunc cb) { mDeviceAddedCb = cb; }
-    void setDeviceRemovedCallback(DeviceCbFunc cb) { mDeviceRemovedCb = cb; }
+    void setInputCallback(const InputCbFunc& cb) { mInputCb = cb; }
+    void setDeviceAddedCallback(const DeviceCbFunc& cb) { mDeviceAddedCb = cb; }
+    void setDeviceRemovedCallback(const DeviceCbFunc& cb) { mDeviceRemovedCb = cb; }
 
     virtual void onInputEvent(const std::shared_ptr<InputDeviceNode>& node, InputEvent& event,
             nsecs_t event_time) override {