diff --git a/fasm/lib/itoa.inc b/fasm/lib/itoa.inc
index 9eab9bf..af315c6 100644
--- a/fasm/lib/itoa.inc
+++ b/fasm/lib/itoa.inc
@@ -1,13 +1,7 @@
 ;; rax contains the integer
 ;; rbx contains a pointer to the string buffer
 itoa:
-   ;; Fill 6 digits with zeroes
    mov byte [rbx], '0'
-   mov byte [rbx + 1], '0'
-   mov byte [rbx + 2], '0'
-   mov byte [rbx + 3], '0'
-   mov byte [rbx + 4], '0'
-   mov byte [rbx + 5], '0'
 
    ;; Special case for the number '0'
    cmp rax, 0
@@ -16,6 +10,13 @@ itoa:
    ret
 
 .not_zero:
+   ;; Fill 6 digits with zeroes
+   mov byte [rbx + 1], '0'
+   mov byte [rbx + 2], '0'
+   mov byte [rbx + 3], '0'
+   mov byte [rbx + 4], '0'
+   mov byte [rbx + 5], '0'
+
    sub rax, 100000
    inc byte [rbx]
    cmp rax, 0