diff --git a/nusamai/src/sink/cesiumtiles/slice.rs b/nusamai/src/sink/cesiumtiles/slice.rs
index 87468268..d03c970c 100644
--- a/nusamai/src/sink/cesiumtiles/slice.rs
+++ b/nusamai/src/sink/cesiumtiles/slice.rs
@@ -423,6 +423,7 @@ fn slice_polygon(
                     let snapped_vertex = snap_to_tile_boundary(vertex, &tile_bounds);
                     ring_buffer.push(snapped_vertex);
                 }
+                poly_buf.add_ring(ring_buffer.drain(..));
             }
 
             send_polygon(key, &poly_buf);