diff --git a/UI.hpp b/UI.hpp
index 7a9cd75..2379480 100644
--- a/UI.hpp
+++ b/UI.hpp
@@ -75,7 +75,7 @@ extern uint8_t seq_data[10][16];
 extern uint8_t seq_vel[10][16];
 extern uint8_t seq_patternchain[4][4];
 extern uint8_t seq_content_type[10];
-extern uint8_t seq_track_type[];
+extern uint8_t seq_track_type[4];
 extern uint8_t seq_step;
 extern uint8_t seq_chord_key_ammount;
 extern int seq_tempo_ms;