diff --git a/spec/15a_binary_game_spec.rb b/spec/15a_binary_game_spec.rb
index 62a2272..ab383c0 100644
--- a/spec/15a_binary_game_spec.rb
+++ b/spec/15a_binary_game_spec.rb
@@ -280,7 +280,11 @@
 
     # Write a test for the following context.
     context 'when game minimum and maximum is 100 and 600' do
-      xit 'returns 9' do
+      subject(:game_six_hundred) { described_class.new(100, 600) }
+
+      it 'returns 9' do
+        max = game_six_hundred.maximum_guesses
+        expect(max).to eq(9)
       end
     end
   end