diff --git a/modules/dnn/test/cnpy.cpp b/modules/dnn/test/cnpy.cpp
index bd5aaddd8..1fc25dfd4 100644
--- a/modules/dnn/test/cnpy.cpp
+++ b/modules/dnn/test/cnpy.cpp
@@ -9,9 +9,19 @@
 #include<cstring>
 #include<iomanip>
 
+#ifdef __GNUC__
+#  pragma GCC diagnostic ignored "-Wunused-but-set-variable"
+#endif
+
 char cnpy::BigEndianTest() {
-    unsigned char x[] = {1,0};
-    short y = *(short*) x;
+    union
+    {
+        unsigned char x[2];
+        short y;
+    };
+    x[0] = 1;
+    x[1] = 0;
+
     return y == 1 ? '<' : '>';
 }
 
diff --git a/modules/dnn/test/cnpy.h b/modules/dnn/test/cnpy.h
index dfddde7e4..1f6c7062e 100644
--- a/modules/dnn/test/cnpy.h
+++ b/modules/dnn/test/cnpy.h
@@ -150,7 +150,7 @@ namespace cnpy {
         std::vector<char> npy_header = create_npy_header(data,shape,ndims);
 
         unsigned long nels = 1;
-        for (int m=0; m<ndims; m++ ) nels *= shape[m];
+        for (unsigned m=0; m<ndims; m++ ) nels *= shape[m];
         int nbytes = nels*sizeof(T) + npy_header.size();
 
         //get the CRC of the data to be added