diff --git a/paddle/platform/device_context_test.cc b/paddle/platform/device_context_test.cc
index af2ce17fc2238dda62e9888ebe9426edcd55d2bc..65345c433c0a328e7f89038a39312edba35eb8c7 100644
--- a/paddle/platform/device_context_test.cc
+++ b/paddle/platform/device_context_test.cc
@@ -15,24 +15,28 @@ limitations under the License. */
 #include "paddle/platform/device_context.h"
 #include "gtest/gtest.h"
 
-using DEVICE_GPU = Eigen::GpuDevice;
 TEST(Device, Init) {
+  using paddle::platform::DeviceContext;
+  using paddle::platform::CUDADeviceContext;
+  using paddle::platform::GPUPlace;
+
   int count = paddle::platform::GetDeviceCount();
   for (int i = 0; i < count; i++) {
-    paddle::platform::DeviceContext* device_context =
-        new paddle::platform::CUDADeviceContext(i);
+    DeviceContext* device_context = new CUDADeviceContext(GPUPlace(i));
     Eigen::GpuDevice* gpu_device =
-        device_context->template get_eigen_device<DEVICE_GPU>();
+        device_context->template get_eigen_device<Eigen::GpuDevice>();
     ASSERT_NE(nullptr, gpu_device);
     delete device_context;
   }
 }
 
 TEST(Device, CUDADeviceContext) {
+  using paddle::platform::CUDADeviceContext;
+  using paddle::platform::GPUPlace;
+
   int count = paddle::platform::GetDeviceCount();
   for (int i = 0; i < count; i++) {
-    paddle::platform::CUDADeviceContext* device_context =
-        new paddle::platform::CUDADeviceContext(i);
+    CUDADeviceContext* device_context = new CUDADeviceContext(GPUPlace(i));
     Eigen::GpuDevice* gpu_device = device_context->eigen_device();
     ASSERT_NE(nullptr, gpu_device);
     cudnnHandle_t cudnn_handle = device_context->cudnn_handle();
diff --git a/paddle/string/piece.h b/paddle/string/piece.h
index 7deeacd8ca99da21a34913c67aa66ece0bd7d495..03ae9243a4cc4e9e92e376bf46ab2b1d7162dfcb 100644
--- a/paddle/string/piece.h
+++ b/paddle/string/piece.h
@@ -39,8 +39,8 @@ public:
   // size_ is 0.
   Piece();
   Piece(const char* d, size_t n);
-  explicit Piece(const char* d);
-  explicit Piece(const std::string& s);
+  Piece(const char* d);         // NOLINT: accept C string into Piece.
+  Piece(const std::string& s);  // NOLINT: accept C++ string into Piece.
 
   const char* data() const { return data_; }
   size_t len() const { return size_; }