diff --git a/modules/imgproc/src/cornersubpix.cpp b/modules/imgproc/src/cornersubpix.cpp
index af5bd999dc..fa4380e368 100644
--- a/modules/imgproc/src/cornersubpix.cpp
+++ b/modules/imgproc/src/cornersubpix.cpp
@@ -96,7 +96,11 @@ void cv::cornerSubPix( InputArray _image, InputOutputArray _corners,
     for( int pt_i = 0; pt_i < count; pt_i++ )
     {
         Point2f cT = corners[pt_i], cI = cT;
-        CV_Assert( Rect(0, 0, src.cols, src.rows).contains(cT) );
+        if (!Rect(0, 0, src.cols, src.rows).contains(cT))
+        {
+            CV_Error(Error::StsOutOfRange,
+                    "cornerSubPix: initial corner is outside the image.");
+        }
         int iter = 0;
         double err = 0;