diff --git a/frappe/patches.txt b/frappe/patches.txt
index 0e02423639..cbda8cf677 100644
--- a/frappe/patches.txt
+++ b/frappe/patches.txt
@@ -272,3 +272,4 @@ execute:frappe.delete_doc_if_exists('DocType', 'GCalendar Account')
 execute:frappe.delete_doc_if_exists('DocType', 'GCalendar Settings')
 frappe.patches.v12_0.remove_parent_and_parenttype_from_print_formats
 execute:from frappe.desk.page.setup_wizard.install_fixtures import update_genders;update_genders()
+frappe.patches.v13_0.website_theme_custom_scss
diff --git a/frappe/patches/v13_0/website_theme_custom_scss.py b/frappe/patches/v13_0/website_theme_custom_scss.py
new file mode 100644
index 0000000000..72c98bfc88
--- /dev/null
+++ b/frappe/patches/v13_0/website_theme_custom_scss.py
@@ -0,0 +1,9 @@
+import frappe
+
+def execute():
+	for theme in frappe.get_all('Website Theme'):
+		doc = frappe.get_doc('Website Theme', theme.name)
+		if not doc.custom_scss and doc.theme_scss:
+			# move old theme to new theme
+			doc.custom_scss = doc.theme_scss
+			doc.save()
\ No newline at end of file