diff --git a/ports/nrf/common-hal/alarm/SleepMemory.h b/ports/nrf/common-hal/alarm/SleepMemory.h
index ea3d40c35a..24fe0065d0 100644
--- a/ports/nrf/common-hal/alarm/SleepMemory.h
+++ b/ports/nrf/common-hal/alarm/SleepMemory.h
@@ -29,8 +29,7 @@
 
 #include "py/obj.h"
 
-// not implemented yet
-#define SLEEP_MEMORY_LENGTH (4)
+#define SLEEP_MEMORY_LENGTH (256)
 
 typedef struct {
     mp_obj_base_t base;