diff --git a/cubesatsim/cubesatsim.h b/cubesatsim/cubesatsim.h
index db9a3a25..aa21abb6 100644
--- a/cubesatsim/cubesatsim.h
+++ b/cubesatsim/cubesatsim.h
@@ -209,7 +209,7 @@ void write_config_file();
 void read_mode(); 
 void write_mode(); 
 void start_clockgen();
-
+bool TimerHandler1(struct repeating_timer *t);
 
 #ifndef STASSID
 #define STASSID "Pico"