diff --git a/src/kiri/core/codec.js b/src/kiri/core/codec.js
index 1ad844ac..ec0da847 100644
--- a/src/kiri/core/codec.js
+++ b/src/kiri/core/codec.js
@@ -261,6 +261,7 @@ Slice.prototype.encode = function(state) {
         index: this.index,
         layers: encode(this.layers, state)
     };
+    if (this.angle !== undefined) rv.angle = this.angle;
     // aggressively free memory
     if (freeMem) this.layers = undefined;
     return rv;
@@ -269,6 +270,7 @@ Slice.prototype.encode = function(state) {
 registerDecoder(TYPE.SLICE, function(v, state) {
     let slice = newSlice(v.z, state.mesh ? state.mesh.newGroup() : null);
 
+    if (v.angle !== undefined) slice.angle = v.angle;
     slice.index = v.index;
     slice.layers = decode(v.layers, state)
 
diff --git a/src/kiri/mode/cam/slice.js b/src/kiri/mode/cam/slice.js
index ddc9a8d2..768ff0bf 100644
--- a/src/kiri/mode/cam/slice.js
+++ b/src/kiri/mode/cam/slice.js
@@ -294,6 +294,9 @@ export async function cam_slice(settings, widget, onupdate, ondone) {
         }
         sliceAll.appendAll(slices);
         if (addIndexing && axisIndex !== undefined) {
+            for (let slice of slices) {
+                slice.angle = axisIndex;
+            }
             // update slice cam lines to add axis indexing
             for (let slice of slices.filter(s => s.camLines)) {
                 addPolyIndexing(slice.camLines, -axisIndex);