diff --git a/SheepShaver/src/timer.cpp b/SheepShaver/src/timer.cpp
index 93a906f0..5e8b6815 100644
--- a/SheepShaver/src/timer.cpp
+++ b/SheepShaver/src/timer.cpp
@@ -573,6 +573,7 @@ static void *timer_func(void *arg)
 		}
 		semaphore_signal(wakeup_time_sem);
 	}
+	return NULL;
 }
 #endif