diff --git a/lib/decisiontree/id3_tree.rb b/lib/decisiontree/id3_tree.rb
index 8f9a7e8..04c9191 100755
--- a/lib/decisiontree/id3_tree.rb
+++ b/lib/decisiontree/id3_tree.rb
@@ -42,6 +42,7 @@ module DecisionTree
     end
 
     def train(data=@data, attributes=@attributes, default=@default)
+      attributes = attributes.map {|e| e.to_s}
       initialize(attributes, data, default, @type)
 
       # Remove samples with same attributes leaving most common classification
diff --git a/spec/id3_spec.rb b/spec/id3_spec.rb
index 5eb67ba..b86b802 100644
--- a/spec/id3_spec.rb
+++ b/spec/id3_spec.rb
@@ -89,4 +89,20 @@ describe describe DecisionTree::ID3Tree do
     Then { tree.predict(["a1","b0","c0"]).should == "RED" }
   end
 
+  describe "numerical labels case" do
+    Given(:labels) { [1, 2] }
+    Given(:data) do
+      [
+        [1, 1, true],
+        [1, 2, false],
+        [2, 1, false],
+        [2, 2, true]
+      ]
+    end
+    Given(:tree) { DecisionTree::ID3Tree.new labels, data, nil, :discrete }
+    When { tree.train }
+    Then {
+      lambda { tree.predict([1, 1]) }.should_not raise_error
+    }
+  end
 end