diff --git a/src/boards/mcu/rak11300/SimpleTimer.h b/src/boards/mcu/rak11300/SimpleTimer.h
index e5def9a..65cb6bc 100644
--- a/src/boards/mcu/rak11300/SimpleTimer.h
+++ b/src/boards/mcu/rak11300/SimpleTimer.h
@@ -111,7 +111,7 @@ class SimpleTimer
 	volatile timer_callback callbacks[MAX_TIMERS];
 
 	// delay values
-	volatile long delays[MAX_TIMERS];
+	volatile unsigned long delays[MAX_TIMERS];
 
 	// number of runs to be executed for each timer
 	volatile int maxNumRuns[MAX_TIMERS];
@@ -129,4 +129,4 @@ class SimpleTimer
 	int numTimers;
 };
 
-#endif
\ No newline at end of file
+#endif