diff --git a/lib/pp.rb b/lib/pp.rb
index a410a0d04a..ce282bee00 100644
--- a/lib/pp.rb
+++ b/lib/pp.rb
@@ -100,6 +100,7 @@ class PP < PrettyPrint
       def sharing_detection
         Ractor.current[:pp_sharing_detection]
       end
+      # Sets the sharing detection flag to b.
       def sharing_detection=(b)
         Ractor.current[:pp_sharing_detection] = b
       end