diff --git a/pep-0520.txt b/pep-0520.txt
index 65a5b6e4b..dbd56ca86 100644
--- a/pep-0520.txt
+++ b/pep-0520.txt
@@ -85,8 +85,8 @@ default behavior::
        ham = None
        eggs = 5
        __definition_order__ = tuple(k for k in locals()
-                                    if (not k.startswith('__') or
-                                        not k.endswith('__')))
+                                    if not (k.startswith('__') and
+                                            k.endswith('__')))
 
 Note that [pep487_] proposes a similar solution, albeit as part of a
 broader proposal.