diff --git a/src/rp2_common/pico_sleep/include/pico/sleep.h b/src/rp2_common/pico_sleep/include/pico/sleep.h
index e061182..65cecc6 100755
--- a/src/rp2_common/pico_sleep/include/pico/sleep.h
+++ b/src/rp2_common/pico_sleep/include/pico/sleep.h
@@ -9,7 +9,7 @@
 
 #include "pico.h"
 #include "hardware/rosc.h"
-
+#include "hardware/timer.h"
 #include "pico/aon_timer.h"
 
 #ifdef __cplusplus