diff --git a/firmware.asm b/firmware.asm
index 5b8307b..ba8fa8c 100644
--- a/firmware.asm
+++ b/firmware.asm
@@ -85,14 +85,6 @@
   pop r16
 .endm
 
-.macro clr_btn_flag
-  push r16
-  lds r16, BTN_FLAGS_ADDRESS
-  cbr r16, @0
-  sts BTN_FLAGS_ADDRESS, r16
-  pop r16
-.endm
-
 .dseg                       ; Data segment
 .org	SRAM_START
 
@@ -108,12 +100,29 @@ BTN_FLAGS_ADDRESS: .byte 0x01
 .cseg                       ; Code segment
 .org 0x00                   ; Start program at 0x00
 
-rjmp start
-rjmp PCINT4_ISR
+;
+; Setup vectors
+rjmp start                  ; Program start at RESET vector
+reti                        ; External Interrupt Request 0
+rjmp PCINT0_ISR             ; Pin Change Interrupt Request 0 / active
+reti                        ; Pin Change Interrupt Request 1 / inactive
+reti                        ; Watchdog Time-out / inactive
+reti                        ; Timer/Counter1 Capture Event / inactive
+reti                        ; Timer/Counter1 Compare Match A / inactive
+reti                        ; Timer/Counter1 Compare Match B / inactive
+reti                        ; Timer/Counter1 Overflow / inactive
+reti                        ; Timer/Counter0 Compare Match A / inactive
+reti                        ; Timer/Counter0 Compare Match B / inactive
+reti                        ; Timer/Counter0 Overflow / inactive
+reti                        ; Analog Comparator / inactive
+reti                        ; ADC Conversion Complete / inactive
+reti                        ; EEPROM Ready / inactive
+reti                        ; USI START / inactive
+reti                        ; USI Overflow / inactive
 
 ;
 ; Interrupt service routines
-PCINT4_ISR:                 ; First button
+PCINT0_ISR:                 ; Button handlers there
   set_btn_flag 0x01
 reti
 
@@ -216,8 +225,6 @@ delay_before_start:
 ret
 
 init_interrupts:
-  push r16
-
   ;
   ; Enable Port Change Interrupt
   ldi r16, (1<<PCIE0)
@@ -225,18 +232,14 @@ init_interrupts:
 
   ;
   ; Set Pin Change Mask Register
-  ldi r16, (1<<PCINT4) | (1<<PCINT5) | (1<<PCINT6) | (1<<PCINT7)
+  ldi r16, (1<<PCINT4) | (1<<PCINT5)| (1<<PCINT6)| (1<<PCINT7)
   out PCMSK0, r16
   clr r16
 
   sei                       ; Enable Global Interrupts
-
-  pop r16
 ret
 
 init_ports:                 ; Init MCU ports
-  push r16
-
   ; Setup PORTA 
   ldi r16, 0x0f
   out DDRA, r16             ; Set directions of leds and buttons
@@ -246,8 +249,6 @@ init_ports:                 ; Init MCU ports
   ; Setup PORTB
   sbi DDRB, BUZZ_PIN        ; Set direction of buzzer pin to output
   cbi PORTB, BUZZ_PIN       ; Set low signal on buzzer
-
-  pop r16
 ret 
 
 delay_50ms:                 ; For 1MHz frequency
diff --git a/firmware.hex b/firmware.hex
index 184b198..ee0050e 100644
--- a/firmware.hex
+++ b/firmware.hex
@@ -1,24 +1,25 @@
 :020000020000FC
-:100000000AC000C00F9301E0009362000F911895A1
-:1000100020E0209362000FED0DBF0F930091600070
-:10002000009361000F9301E0009360000F910F9126
-:1000300000916000013061F441D00F9300916000A5
-:10004000009361000F9302E0009360000F910F9105
-:10005000023041F420916200213019F4DA9A4AD03A
-:1000600001C0DA98033001F4043001F4E1CF1F93AA
-:100070002F933F934F934BB30F9301EF0BBB0F9114
-:1000800039D011E033E020EF110F210F2BBB32D01C
-:100090003A95C9F70F9308EF0BBB0F912BD018E0DF
-:1000A00033E020EF1695210F2BBB24D03A95C9F7EA
-:1000B0004BBB4F913F912F911F91089512D008D0C3
-:1000C00001D0089516E0D3DF1A95E9F71FD00895FF
-:1000D0000F9300E10BBF00EF02BB002778940F9154
-:1000E00008950F930FE00ABB02950BBBBA9AC29812
-:1000F0000F9108952F933F9321E43FEE3A95F1F746
-:100100002A95E1F700003F912F9108958F939F93D7
-:1001100024E683EC99E00197F1F72A95D1F724E6DC
-:100120009F918F9108954D656D6F7279206C656414
-:100130002067616D652E205772697474656E206248
-:100140007920536572676579205961726B6F7620EB
-:0A01500032372E30392E32303231B2
+:1000000019C018950EC0189518951895189518953B
+:100010001895189518951895189518951895189578
+:1000200018950F9301E0009362000F91189520E05E
+:10003000209362000FED0DBF0F93009160000093BD
+:1000400061000F9301E0009360000F910F91009108
+:100050006000013061F441D00F9300916000009383
+:1000600061000F9302E0009360000F910F91023046
+:1000700041F420916200213019F4DA9A46D001C08F
+:10008000DA98033001F4043001F4E1CF1F932F9389
+:100090003F934F934BB30F9301EF0BBB0F9135D0B1
+:1000A00011E033E020EF110F210F2BBB2ED03A953A
+:1000B000C9F70F9308EF0BBB0F9127D018E033E07F
+:1000C00020EF1695210F2BBB20D03A95C9F74BBBDB
+:1000D0004F913F912F911F91089510D008D001D0DA
+:1000E000089516E0D3DF1A95E9F71BD0089500E1D3
+:1000F0000BBF00EF02BB0027789408950FE00ABB06
+:1001000002950BBBBA9AC29808952F933F9321E4AE
+:100110003FEE3A95F1F72A95E1F700003F912F91D4
+:1001200008958F939F9324E683EC99E00197F1F76C
+:100130002A95D1F724E69F918F9108954D656D6FB3
+:100140007279206C65642067616D652E2057726935
+:100150007474656E206279205365726765792059E1
+:1001600061726B6F762032372E30392E3230323159
 :00000001FF