diff --git a/modules/core/src/convert_c.cpp b/modules/core/src/convert_c.cpp
index 96beffccc6..ae93a73ebb 100644
--- a/modules/core/src/convert_c.cpp
+++ b/modules/core/src/convert_c.cpp
@@ -83,7 +83,9 @@ cvMixChannels( const CvArr** src, int src_count,
                CvArr** dst, int dst_count,
                const int* from_to, int pair_count )
 {
-    cv::AutoBuffer<cv::Mat> buf(src_count + dst_count);
+    CV_Assert(src_count >= 0 && dst_count >= 0);
+    size_t buf_size = static_cast<size_t>(src_count) + static_cast<size_t>(dst_count);
+    cv::AutoBuffer<cv::Mat> buf(buf_size);
 
     int i;
     for( i = 0; i < src_count; i++ )