diff --git a/avr/modules/ma_light/main.asm b/avr/modules/ma_light/main.asm
index fb66b5a..03d0c90 100644
--- a/avr/modules/ma_light/main.asm
+++ b/avr/modules/ma_light/main.asm
@@ -8,7 +8,10 @@
 ; ***************************************************************************
 
 
-.equ MOTIONLIGHT_DEFAULT_ONTIME      = 3000 ; 5min
+; ***************************************************************************
+; defines
+
+.equ MOTIONLIGHT_DEFAULT_ONTIME      = 3000 ; 5min (in 1/10 secs)
 
 .equ MOTIONLIGHT_SOURCE_NUM          = 2
 
@@ -17,6 +20,10 @@
 .equ MOTIONLIGHT_SOURCE_SIZE         = 2
 
 
+
+; ***************************************************************************
+; data
+
 .dseg
 
 
@@ -30,6 +37,9 @@ motionLightDataEnd:
 
 
 
+; ***************************************************************************
+; code
+
 .cseg
 
 MOTIONLIGHT_BEGIN:
@@ -88,15 +98,12 @@ MotionLight_Fini:
 MotionLight_Every100ms:
   lds r24, motionLightTimer
   lds r25, motionLightTimer+1
-  mov r16, r24
-  or r16, r25
-  brne MotionLight_Every100ms_dec
-  ret
-MotionLight_Every100ms_dec:
   sbiw r25:r24, 1
+  brcs MotionLight_Every100ms_ret
   sts motionLightTimer, r24
   sts motionLightTimer+1, r25
   breq MotionLight_Every100ms_off
+MotionLight_Every100ms_ret:
   ret
 MotionLight_Every100ms_off:
   rjmp motionLightTurnOff   ; (r16, r17, r18, r19, r20, r21, r23)