diff --git a/include/voicemanager.h b/include/voicemanager.h
index a3a113e..fb401db 100644
--- a/include/voicemanager.h
+++ b/include/voicemanager.h
@@ -2,10 +2,11 @@
 #define __VOICEMANAGER_H__
 
 #include <unordered_set>
+#include <thread>
 
 #include "voice.h"
 
-#define NUM_VOICES 16
+#define NUM_VOICES 24
 
 class VoiceManager {
 public:
@@ -31,4 +32,4 @@ private:
     unsigned int scoreVoice(VoiceData& voiceData);
 };
 
-#endif
\ No newline at end of file
+#endif