diff --git a/src/cljs/emptyhead/thought/eval.cljs b/src/cljs/emptyhead/thought/eval.cljs
index 8cabd65..98d5cb3 100644
--- a/src/cljs/emptyhead/thought/eval.cljs
+++ b/src/cljs/emptyhead/thought/eval.cljs
@@ -14,12 +14,14 @@
     (if-not impl-idea
       (logging/error (str "No implementation for thought `" (thought/operator thought) "`.")
                      {:thought thought :parent parent :type :unimplemented-thought})
-      ((:implementation impl-idea) thought parent))))
+      ((prtc/val-fn :implementation impl-idea) thought parent))))
 
+;; FIXME I don't think omitting the parent here is actually valid?
+;; might need to use thought.crud/root-thought, but better making parent mandatory tabun
 (defn execute!
   "Execute `thought` with `parent`, applying aspects to `thought` according to its :extension-stages.
   Returns (potentially modified) `parent`."
-  [thought parent]
+  [thought & [parent]]
   (loop [th (prtc/val-fn #(assoc % :_parent (prtc/value parent)) thought)
          parent parent]
     (let [[extensions th cur] (extend/pop-stage th)
diff --git a/src/cljs/emptyhead/thought/return.cljs b/src/cljs/emptyhead/thought/return.cljs
index e666311..22a54c5 100644
--- a/src/cljs/emptyhead/thought/return.cljs
+++ b/src/cljs/emptyhead/thought/return.cljs
@@ -3,11 +3,11 @@
   (:require [emptyhead.idea.protocol :as prtc]))
 
 (defn with-return
-  "Returns a copy of the thought with all values in data
+  "Returns the thought with all values in data
    added to the top of its stack."
   [thought data]
   (if (first data)
-    (prtc/copy-fn
+    (prtc/val-fn
      #(update % :return (fnil into []) data) thought)
     thought))