diff --git a/modules/core/src/matrix.cpp b/modules/core/src/matrix.cpp
index 135397aa7d281b533d5a565e0cd692f8c186be29..2e479f7c5676d9aed208fe3ca716c105d53f9366 100644
--- a/modules/core/src/matrix.cpp
+++ b/modules/core/src/matrix.cpp
@@ -1395,7 +1395,7 @@ void _InputArray::getMatVector(std::vector<Mat>& mv) const
     {
         const std::vector<uchar>& v = *(const std::vector<uchar>*)obj;
 
-        size_t n = v.size(), esz = CV_ELEM_SIZE(flags);
+        size_t n = size().width, esz = CV_ELEM_SIZE(flags);
         int t = CV_MAT_DEPTH(flags), cn = CV_MAT_CN(flags);
         mv.resize(n);