diff --git a/railties/lib/rails/code_statistics.rb b/railties/lib/rails/code_statistics.rb
index 28a64e1cb3..cf7bca9d51 100644
--- a/railties/lib/rails/code_statistics.rb
+++ b/railties/lib/rails/code_statistics.rb
@@ -35,7 +35,7 @@ class CodeStatistics #:nodoc:
 
   private
     def calculate_statistics
-      @pairs.transform_values { |dir| calculate_directory_statistics(dir) }
+      Hash[@pairs.map { |pair| [pair.first, calculate_directory_statistics(pair.last)] }]
     end
 
     def calculate_directory_statistics(directory, pattern = /^(?!\.).*?\.(rb|js|coffee|rake)$/)