diff --git a/modules/dnn/misc/python/test/test_dnn.py b/modules/dnn/misc/python/test/test_dnn.py
index 54b51b4133..5c91aae56f 100644
--- a/modules/dnn/misc/python/test/test_dnn.py
+++ b/modules/dnn/misc/python/test/test_dnn.py
@@ -446,5 +446,11 @@ class dnn_test(NewOpenCVTests):
 
             normAssert(self, real_output, gold_output, "", getDefaultThreshold(target))
 
+    def test_scalefactor_assign(self):
+        params = cv.dnn.Image2BlobParams()
+        self.assertEqual(params.scalefactor, (1.0, 1.0, 1.0, 1.0))
+        params.scalefactor = 2.0
+        self.assertEqual(params.scalefactor, (2.0, 0.0, 0.0, 0.0))
+
 if __name__ == '__main__':
     NewOpenCVTests.bootstrap()
diff --git a/modules/python/src2/cv2_convert.cpp b/modules/python/src2/cv2_convert.cpp
index f2be05d92d..f03a2e2d86 100644
--- a/modules/python/src2/cv2_convert.cpp
+++ b/modules/python/src2/cv2_convert.cpp
@@ -327,7 +327,7 @@ bool pyopencv_to(PyObject *o, Scalar& s, const ArgInfo& info)
         }
     } else {
         if (PyFloat_Check(o) || PyInt_Check(o)) {
-            s[0] = PyFloat_AsDouble(o);
+            s = PyFloat_AsDouble(o);
         } else {
             failmsg("Scalar value for argument '%s' is not numeric", info.name);
             return false;