diff --git a/src/day8/re_frame/trace/app_state.cljs b/src/day8/re_frame/trace/app_state.cljs
index a9ba389..97d72f3 100644
--- a/src/day8/re_frame/trace/app_state.cljs
+++ b/src/day8/re_frame/trace/app_state.cljs
@@ -22,7 +22,7 @@
 (defn data-structure
   [jsonml]
   (let [expand? (r/atom true)]
-    (fn []
+    (fn [jsonml]
       [:span
         {:class (str/join " " ["re-frame-trace--object"
                                (when @expand? "expanded")])