diff --git a/Doc/library/dataclasses.rst b/Doc/library/dataclasses.rst
index b26f6422db917a..9e3c792fd106c7 100644
--- a/Doc/library/dataclasses.rst
+++ b/Doc/library/dataclasses.rst
@@ -532,7 +532,7 @@ Mutable default values
      class C:
          x = []
          def add(self, element):
-             self.x += element
+             self.x.append(element)
 
      o1 = C()
      o2 = C()