diff --git a/avr/devices/all/hw_m8515.asm b/avr/devices/all/hw_m8515.asm
index 8df7e0e..040bc8e 100644
--- a/avr/devices/all/hw_m8515.asm
+++ b/avr/devices/all/hw_m8515.asm
@@ -68,20 +68,27 @@ systemSetSpeed:
 systemSleep:
   ; only modify SE, SM2, SM1 and SM0
   cli
+
   M_IO_READ r16, MCUCR
   cbr r16, (1<<SE) | (1<<SM2) | (1<<SM1)
   M_IO_WRITE MCUCR, r16
+
   M_IO_READ r16, EMCUCR
   cbr r16, (1<<SM0)
   M_IO_WRITE EMCUCR, r16
+
   sei                        ; make sure interrupts really are enabled
+
   M_IO_READ r16, MCUCR       ; enable sleep mode
   sbr r16, (1<<SE)
   M_IO_WRITE MCUCR, r16
+
   sleep                      ; sleep, wait for interrupt
+
   M_IO_READ r16, MCUCR       ; disable sleep mode
   cbr r16, (1<<SE)
   M_IO_WRITE MCUCR, r16
+
   ret
 ; @end