diff --git a/package.json b/package.json
index e7df7fe3c..f6a79f5d2 100644
--- a/package.json
+++ b/package.json
@@ -16,6 +16,7 @@
   "homepage": "https://github.com/bryphe/revery#readme",
   "esy": {
     "build": [ "dune build --root . -j4" ],
+    "buildsInSource": "_build",
     "install": [
       "esy-installer Revery.install",
       "esy-installer Revery_Core.install",
diff --git a/src/UI/Revery_UI.re b/src/UI/Revery_UI.re
index dfe287b4c..c22dd6665 100644
--- a/src/UI/Revery_UI.re
+++ b/src/UI/Revery_UI.re
@@ -90,6 +90,7 @@ let start =
     Revery_Core.Event.subscribe(
       window.onMouseWheel,
       m => {
+        print_endline ("Revery::onMouseWheel - " ++ string_of_float(m.deltaY));
         let evt = Revery_Core.Events.InternalMouseWheel(m);
         Mouse.dispatch(mouseCursor, evt, rootNode);
       },