diff --git a/cpu/avr/rtimer-arch.h b/cpu/avr/rtimer-arch.h
index 976cf152b..6c0d73b54 100644
--- a/cpu/avr/rtimer-arch.h
+++ b/cpu/avr/rtimer-arch.h
@@ -1,4 +1,6 @@
 #ifndef __RTIMER_ARCH_H__
 #define __RTIMER_ARCH_H__
 
+#define RTIMER_ARCH_SECOND 1 /* TODO Implement? */
+
 #endif /* __RTIMER_ARCH_H__ */