diff --git a/src/kiri/platform.js b/src/kiri/platform.js
index 9ab5d757..39421bf2 100644
--- a/src/kiri/platform.js
+++ b/src/kiri/platform.js
@@ -90,7 +90,7 @@ function platformUpdateTopZ(zdelta) {
     const hasStock = stock.x && stock.y && stock.z;
     const MODE = get_mode();
     api.widgets.each(widget => {
-        if (MODE === MODES.CAM) {
+        if (MODE === MODES.CAM && hasStock) {
             const bounds = widget.getBoundingBox();
             const wzmax = bounds.max.z;
             const zdelta = process.camZOffset || 0;