itoa function in asm

section .text
  global _start

%include "includes/print.asm"      ; syscall to print to screen function
%include "includes/leave.asm"      ; syscall to exit program

_start:

  mov ebx, 0                       ; i = 0 in loop

itoa_start:

  xor edx, edx                     ; clear edx
  mov eax, [num]                   ; move value of num into eax
  mov ecx, 10                      ; move 10 into ecx (divisor)
  div ecx                          ; div ecx (ex. 1234 / 10 = 1234.5)
  cmp edx, 0                       ; compare remainder (edx ex. .5) to 0
  je itoa_end                      ; if remainder == 0 jump to end label
  mov [num], eax                   ; move quotient (eax ex. 1234) into num (12345 -> 1234)
  add edx, '0'                     ; add '0' (48) to remainder to convert into ASCII (5 -> '5')
  mov [res + ebx], edx             ; move remainder into res value + ebx (ex. res + 0 -> '5')
  add ebx, 1                       ; increase ebx value by 1

  jmp itoa_start
itoa_end:
  add ebx, 1                       ; increase ebx value by 1 for terminating string
  mov word [res + ebx], 0          ; move 0 (terminator) into res + ebx

  mov ecx, res
  mov edx, 5
  call print                       ; print res string

  call leave

section .data
  ; msg db "Enter num: "           ; Uncommenting this and running works as expected
  ; msg_len equ $ - msg            ; ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

  ; msg db "HELLO"                 ; Uncommenting this and running gives another value (2863)
  ; msg_len equ $ - msg            ; ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
                                   ; Strangely, adding ": " to the end of "HELLO" makes it work fine

  num dw 12345                     ; Defining word num with value 12345

section .bss

  res resw 6                       ; Reserving word of 6 for res variable