diff --git a/django/forms/__init__.py b/django/forms/__init__.py
index 7ad26a4d71..52092aff7b 100644
--- a/django/forms/__init__.py
+++ b/django/forms/__init__.py
@@ -577,7 +577,7 @@ class SelectMultipleField(SelectField):
selected_html = ''
if str(value) in str_data_list:
selected_html = ' selected="selected"'
- output.append(' ' % (escape(value), selected_html, choice))
+ output.append(' ' % (escape(value), selected_html, escape(choice)))
output.append(' ')
return '\n'.join(output)