diff --git a/samples/cpp/cloning_gui.cpp b/samples/cpp/cloning_gui.cpp
index 84458fd4fe..1d742fdd51 100644
--- a/samples/cpp/cloning_gui.cpp
+++ b/samples/cpp/cloning_gui.cpp
@@ -69,6 +69,10 @@ float red, green, blue;
 
 double low_t, high_t;
 
+void source(int, int, int, int, void*);
+void destination(int, int, int, int, void*);
+void checkfile(char*);
+
 void source(int event, int x, int y, int, void*)
 {
 
@@ -304,7 +308,7 @@ void checkfile(char *file)
     }
 }
 
-int main(int argc, char **argv)
+int main()
 {
     cout << endl;
     cout << "Cloning Module" << endl;
diff --git a/samples/cpp/create_mask.cpp b/samples/cpp/create_mask.cpp
index 03055e99e0..59905f1403 100644
--- a/samples/cpp/create_mask.cpp
+++ b/samples/cpp/create_mask.cpp
@@ -36,6 +36,8 @@ int minx,miny,maxx,maxy,lenx,leny;
 
 int channel;
 
+void mouseHandler(int, int, int, int, void*);
+
 void mouseHandler(int event, int x, int y, int, void*)
 {
 
@@ -123,6 +125,13 @@ void mouseHandler(int event, int x, int y, int, void*)
 
 int main(int argc, char **argv)
 {
+
+    if(argc != 2)
+    {
+        cout << "usage: " << argv[0] << " <input_image>" << endl;
+        exit(1);
+    }
+
     Mat src = imread(argv[1]);
 
 	minx = INT_MAX; miny = INT_MAX; maxx = INT_MIN; maxy = INT_MIN;
diff --git a/samples/cpp/npr_demo.cpp b/samples/cpp/npr_demo.cpp
index 871fd32405..e5e2528f13 100644
--- a/samples/cpp/npr_demo.cpp
+++ b/samples/cpp/npr_demo.cpp
@@ -28,19 +28,16 @@ using namespace cv;
 
 int main(int argc, char* argv[])
 {
-    int num,type;
-
-    int flag = 0;
-
-    Mat I = imread(argv[1]);
-
-
     if(argc < 2)
     {
         cout << "usage: " << argv[0] << " <Input image> "  << endl;
         exit(0);
     }
 
+    int num,type;
+
+    Mat I = imread(argv[1]);
+
     if(!I.data)
     {
         cout <<  "Image not found" << endl;