diff -urN a/modules/python/src2/cv2.cpp b/modules/python/src2/cv2.cpp
--- a/modules/python/src2/cv2.cpp	2018-02-23 11:38:33.000000000 +0300
+++ b/modules/python/src2/cv2.cpp	2019-08-10 22:28:03.337071791 +0300
@@ -886,7 +886,7 @@
     (void)name;
     if(!obj || obj == Py_None)
         return true;
-    char* str = PyString_AsString(obj);
+    const char* str = PyString_AsString(obj);
     if(!str)
         return false;
     value = String(str);