diff --git a/messages.asm b/messages.asm
index 49f785e..7a19f21 100644
--- a/messages.asm
+++ b/messages.asm
@@ -8,6 +8,8 @@ VIDEO_MODE equ 0x3		; 80x25 screen, text mode
 PIT_MODECOMMAND_PORT equ 0x43	; programmable interval timer mode/command port (used for speaker)
 PIT_CH2_DATA_PORT equ 0x42	; PIT channel 2 data port
 
+VIRTUAL_KBD_CHAR equ 0x09	; character to detect if a command is comming from the virtual keyboard (htab)
+
 ;; see http://www.ctyme.com/intr/int-10.htm for interrupts
 
 start:
@@ -66,9 +68,9 @@ int 0x10
 	mov ah, 0x00	; Read character
 	int 0x16
 
-	;; a null character will be sent before every command from the virtual keyboard
-	;; so if a null is detected go to the virtual_kbd_loop instead
-	cmp al, 0x00	; null
+	;; a special character will be sent before every command from the virtual keyboard
+	;; so if that character is detected go to the virtual_kbd_loop instead
+	cmp al, VIRTUAL_KBD_CHAR
 	je .virtual_kbd_loop_init
 
 	cmp al, 0x08 	; backspace