diff --git a/rtgui/cropwindow.cc b/rtgui/cropwindow.cc
index 6eac5e59d..50d8f9543 100644
--- a/rtgui/cropwindow.cc
+++ b/rtgui/cropwindow.cc
@@ -1964,7 +1964,7 @@ void CropWindow::zoomIn (bool toCursor, int cursorX, int cursorY)
                 int x1 = cropHandler.cropParams.x + cropHandler.cropParams.w / 2;
                 int y1 = cropHandler.cropParams.y + cropHandler.cropParams.h / 2;
                 double cropd = sqrt(cropHandler.cropParams.h * cropHandler.cropParams.h + cropHandler.cropParams.w * cropHandler.cropParams.w) * zoomSteps[cropZoom].zoom;
-                double imd = sqrt(imgW * imgW + imgH + imgH);
+                double imd = sqrt(imgW * imgW + imgH * imgH);
                 double d;
 
                 // the more we can see of the crop, the more gravity towards crop center