diff --git a/.rubocop.yml b/.rubocop.yml
index c151af379..9b451a5f9 100644
--- a/.rubocop.yml
+++ b/.rubocop.yml
@@ -52,6 +52,8 @@ RBS/Style/EmptyArgument:
   Enabled: true
 RBS/Style/InitializeReturnType:
   Enabled: true
+RBS/Style/OptionalNil:
+  Enabled: true
 
 Lint/DuplicateMethods:
   Enabled: true