diff --git a/modules/gpu/include/opencv2/gpu/device/emulation.hpp b/modules/gpu/include/opencv2/gpu/device/emulation.hpp
index 074e91127..b6fba230e 100644
--- a/modules/gpu/include/opencv2/gpu/device/emulation.hpp
+++ b/modules/gpu/include/opencv2/gpu/device/emulation.hpp
@@ -44,7 +44,6 @@
 #define OPENCV_GPU_EMULATION_HPP_
 
 #include "warp_reduce.hpp"
-#include <stdio.h>
 
 namespace cv { namespace gpu { namespace device
 {
diff --git a/modules/gpu/src/cuda/optical_flow_farneback.cu b/modules/gpu/src/cuda/optical_flow_farneback.cu
index 8231775b8..5bbca34f1 100644
--- a/modules/gpu/src/cuda/optical_flow_farneback.cu
+++ b/modules/gpu/src/cuda/optical_flow_farneback.cu
@@ -42,7 +42,6 @@
 
 #if !defined CUDA_DISABLER
 
-#include <stdio.h>
 #include "internal_shared.hpp"
 #include "opencv2/gpu/device/common.hpp"
 #include "opencv2/gpu/device/border_interpolate.hpp"
@@ -57,8 +56,6 @@
 #define BORDER_SIZE 5
 #define MAX_KSIZE_HALF 100
 
-using namespace std;
-
 namespace cv { namespace gpu { namespace device { namespace optflow_farneback
 {
     __constant__ float c_g[8];
diff --git a/modules/gpu/src/nvidia/core/NCV.cu b/modules/gpu/src/nvidia/core/NCV.cu
index 5d1b5d12c..77e59cc5c 100644
--- a/modules/gpu/src/nvidia/core/NCV.cu
+++ b/modules/gpu/src/nvidia/core/NCV.cu
@@ -45,8 +45,6 @@
 #include <vector>
 #include "NCV.hpp"
 
-using namespace std;
-
 
 //==============================================================================
 //
@@ -55,16 +53,16 @@ using namespace std;
 //==============================================================================
 
 
-static void stdDebugOutput(const string &msg)
+static void stdDebugOutput(const std::string &msg)
 {
-    cout << msg;
+    std::cout << msg;
 }
 
 
 static NCVDebugOutputHandler *debugOutputHandler = stdDebugOutput;
 
 
-void ncvDebugOutput(const string &msg)
+void ncvDebugOutput(const std::string &msg)
 {
     debugOutputHandler(msg);
 }