diff --git a/prelude.rb b/prelude.rb
index 9e94aadf9c..3fdabe81aa 100644
--- a/prelude.rb
+++ b/prelude.rb
@@ -151,4 +151,6 @@ module Kernel
 
   # suppress redefinition warning
   alias pp pp # :nodoc:
+
+  private :pp
 end