diff --git a/cubesatsim/cubesatsim.ino b/cubesatsim/cubesatsim.ino
index 42cb6de7..fc561a87 100644
--- a/cubesatsim/cubesatsim.ino
+++ b/cubesatsim/cubesatsim.ino
@@ -33,6 +33,7 @@
 #include "hardware/irq.h"  // interrupts
 #include "hardware/pwm.h"  // pwm 
 #include "hardware/sync.h" // wait for interrupt 
+#include "RPi_Pico_ISR_Timer.h"
 #include "RPi_Pico_TimerInterrupt.h"
 #include <WiFi.h>
 #include "hardware/gpio.h"