diff --git a/src/heyarne/line_us/gcode.clj b/src/heyarne/line_us/gcode.clj
index ff4b6f2..59ab580 100644
--- a/src/heyarne/line_us/gcode.clj
+++ b/src/heyarne/line_us/gcode.clj
@@ -65,7 +65,7 @@
           result []]
      (cond
        (nil? el) result
-       (sequential? el) (recur rs (vec (concat result (scene->gcode-seq el opts))))    ;; recursively convert sequences
+       (sequential? el) (recur rs (into result (scene->gcode-seq el opts)))            ;; recursively convert sequences
        (geom? el) (recur rs (conj result (if res (gcode-seq el res) (gcode-seq el))))  ;; convert geoms
        (map? el) (recur rs result)))))                                                 ;; ignore attribute maps
 
@@ -106,8 +106,8 @@
   ;;     "G01 X0.8090169943749473 Y-0.5877852522924734 Z0"
   ;;     "G01 X0.9510565162951535 Y-0.3090169943749476 Z0"
   ;;     "G01 X0.9510565162951535 Y-0.3090169943749476 Z1000")
-    ;; `scene->gcode-seq` converts a tree of arbitrarily nested elements into a
-    ;; sequence of gcode drawing instructions
+  ;; `scene->gcode-seq` converts a tree of arbitrarily nested elements into a
+  ;; sequence of gcode drawing instructions
 
   (scene->gcode-seq
    [[(r/rect [0 0] [10 10]) {:attributes/ignored? true}]