diff --git a/avr/devices/all/hw_tn84.asm b/avr/devices/all/hw_tn84.asm
index b093245..dc48906 100644
--- a/avr/devices/all/hw_tn84.asm
+++ b/avr/devices/all/hw_tn84.asm
@@ -72,13 +72,14 @@ systemSleep:
   ; only modify SE, SM1 and SM0
   cli
   in r16, MCUCR
-  ldi r17, (1<<SE) | (1<<SM1) | (1<<SM0)
-  neg r17
-  and r16, r17
-  ori r16, (1<<SE)           ; sleep mode "idle", enable
+  cbr r16, (1<<SE) | (1<<SM1) | (1<<SM0)
+  out MCUCR, r16
+  sbr r16, (1<<SE) | (0<<SM1) | (0<<SM0)  ; sleep mode "idle", enable
   out MCUCR, r16
   sei                        ; make sure interrupts really are enabled
   sleep                      ; sleep, wait for interrupt
+  cbr r16, (1<<SE) | (1<<SM1) | (1<<SM0)
+  out MCUCR, r16
   ret
 ; @end
 
@@ -90,7 +91,7 @@ systemSleep:
 ;
 
 systemSetupTimer0:            ; setup timer for IRQ every 100ms
-  ldi r16, (1<<CS02) | (0<<CS01) | (1<<CS00)  ; Prescaler 1024
+  ldi r16, (0<<WGM02) | (1<<CS02) | (0<<CS01) | (1<<CS00)  ; Prescaler 1024
   out TCCR0B, r16
   
   ldi r16, (1<<WGM01) | (0<<WGM00)             ; CTC mode
@@ -125,19 +126,12 @@ systemSetupTimer0:            ; setup timer for IRQ every 100ms
 
 
   ldi r16, (1<<OCF0A)             ; clear pending interrupts
-.ifdef TIFR0
   out TIFR0, r16
-.else
-  out TIFR, r16
-.endif
   
   ldi r16, (1<<OCIE0A)            ; Timer/Counter0 Output Compare Match A Interrupt Enable
-.ifdef TIMSK0
   out TIMSK0, r16
-.else
-  out TIMSK, r16
-.endif
-  sec
+ 
+ sec
   ret
 ; @end