diff --git a/docs/ref/contrib/messages.txt b/docs/ref/contrib/messages.txt
index aaa2c26a45..4b17b6d4de 100644
--- a/docs/ref/contrib/messages.txt
+++ b/docs/ref/contrib/messages.txt
@@ -388,8 +388,10 @@ method.
         success_message = "%(calculated_field)s was created successfully"
 
         def get_success_message(self, cleaned_data):
-            return self.success_message % dict(cleaned_data,
-                                               calculated_field=self.object.calculated_field)
+            return self.success_message % dict(
+                cleaned_data,
+                calculated_field=self.object.calculated_field,
+            )
 
 Expiration of messages
 ======================