diff --git a/test/dom.nb b/test/dom.nb
new file mode 100644
index 0000000..dfac044
--- /dev/null
+++ b/test/dom.nb
@@ -0,0 +1,16 @@
+---
+starboard:
+  python:
+    execution_mode: "pyodide_webworker"
+---
+# %% [python]
+from js import document
+
+el = document.createElement("h1")
+document.body.append(el);
+# %% [python]
+from js import document
+
+el = document.createElement("h1")
+# el as return value of cell
+el
diff --git a/test/python.nb b/test/python.nb
index 38f7f3d..4ae12dd 100644
--- a/test/python.nb
+++ b/test/python.nb
@@ -1,3 +1,8 @@
+---
+starboard:
+  python:
+    execution_mode: "pyodide_webworker"
+---
 # %%--- [python]
 # properties:
 #   run_on_load: true