diff --git a/src/kiri/slicer2.js b/src/kiri/slicer2.js
index e2cc75a0..ce83376e 100644
--- a/src/kiri/slicer2.js
+++ b/src/kiri/slicer2.js
@@ -194,7 +194,7 @@
                 lines = [],
                 zScale = this.zScale,
                 buckets = this.buckets,
-                bucket = buckets.length ? buckets[Math.floor(z * zScale)] : points;
+                bucket = buckets.length ? buckets[Math.floor(z * zScale)] : this.points;
 
             if (onflat) {
                 z += flatoff;
diff --git a/src/mode/cam/slice.js b/src/mode/cam/slice.js
index a85c6e1f..3fe2aff9 100644
--- a/src/mode/cam/slice.js
+++ b/src/mode/cam/slice.js
@@ -223,6 +223,8 @@
                     }
                 });
 
+                if (!offset) return;
+
                 // add outside pass if not inside only
                 if (!insideOnly) {
                     const outside = POLY.offset(shadow, roughToolDiam * proc.camRoughOver, {z: slice.z});
diff --git a/src/mode/cam/topo.js b/src/mode/cam/topo.js
index 70340495..8add3c4e 100644
--- a/src/mode/cam/topo.js
+++ b/src/mode/cam/topo.js
@@ -293,10 +293,12 @@
             stepsTotal += sindex.length * 2;
             if (proc.camContourXOn) stepsTotal += (maxX-minX) / toolStep;
             if (proc.camContourYOn) stepsTotal += (maxY-minY) / toolStep;
+
             let slices = slicer.slice(sindex, { each: (data, index, total) => {
                 onupdate(++stepsTaken, stepsTotal, "topo slice");
             }, genso: true });
-            processSlices(slices.map(data => data.slice));
+
+            processSlices(slices.filter(s => s.lines).map(data => data.slice));
         }
     }