diff --git a/rubocop.yml b/rubocop.yml
index 3c34711..128c39c 100644
--- a/rubocop.yml
+++ b/rubocop.yml
@@ -439,7 +439,7 @@ Style/PerlBackrefs:
 
 Naming/PredicateName:
   Enabled: True
-  AllowedMethods: ['is_a', 'is_to_s']
+  AllowedMethods: ['is_a?', 'is_to_s']
 
 Style/RedundantException:
   Enabled: True