diff --git a/tool/lib/core_assertions.rb b/tool/lib/core_assertions.rb
index d84b7f555a..3cc1ea11b5 100644
--- a/tool/lib/core_assertions.rb
+++ b/tool/lib/core_assertions.rb
@@ -33,7 +33,7 @@ module Test
     module CoreAssertions
       require_relative 'envutil'
       require 'pp'
-      require 'io/console'
+      nil.pretty_inspect
 
       def mu_pp(obj) #:nodoc:
         obj.pretty_inspect.chomp