diff --git a/wires.js b/wires.js
index ce0065b..8db858f 100644
--- a/wires.js
+++ b/wires.js
@@ -204,8 +204,8 @@ function ctxDrawBox(ctx, xMin, yMin, xMax, yMax){
 function zoomToBox(xmin,xmax,ymin,ymax){
 	var xmid=(xmin+xmax)/2;
 	var ymid=(ymin+ymax)/2;
-	var x=(xmid+400)/grChipSize*600;
-	var y=600-ymid/grChipSize*600;
+	var x=(xmid+grChipOffsetX)/grChipSize*600;
+	var y=600-(ymid-grChipOffsetY)/grChipSize*600;
 	var zoom=5;  // pending a more careful calculation
 	moveHere([x,y,zoom]);
 }