diff --git a/lib/decisiontree/id3_tree.rb b/lib/decisiontree/id3_tree.rb
index 4e4c340..b0702c8 100755
--- a/lib/decisiontree/id3_tree.rb
+++ b/lib/decisiontree/id3_tree.rb
@@ -190,7 +190,7 @@ module DecisionTree
         end
         label_text = "#{key} ''"
         if type(attr[0].attribute) == :continuous
-          label_text.gsub!("''", attr[0].threshold)
+          label_text.gsub!("''", attr[0].threshold.to_s)
         end
 
         [parent_text, child_text, label_text]