diff --git a/lib/decisiontree/id3_tree.rb b/lib/decisiontree/id3_tree.rb
index 9097ebf..8df1483 100755
--- a/lib/decisiontree/id3_tree.rb
+++ b/lib/decisiontree/id3_tree.rb
@@ -120,7 +120,7 @@ def id3_discrete(data, attributes, attribute)
       index = attributes.index(attribute)
 
       values = data.map { |row| row[index] }.uniq
-      remainder = values.sort.sum do |val|
+      remainder = values.sort.inject(0, :+) do |val|
         classification = data.each_with_object([]) do |row, result|
           result << row.last if row[index] == val
         end