diff --git a/docs/advanced_topics/streamfield_migrations.md b/docs/advanced_topics/streamfield_migrations.md
index 86dfb32687..054bb0e00c 100644
--- a/docs/advanced_topics/streamfield_migrations.md
+++ b/docs/advanced_topics/streamfield_migrations.md
@@ -115,6 +115,7 @@ def pagerevision_to_streamfield(revision_data):
 
 
 def page_to_richtext(page):
+    changed = False
     if page.body:
         try:
             body_data = json.loads(page.body)