diff --git a/core.asm b/core.asm
index e3f482f..3bc394d 100644
--- a/core.asm
+++ b/core.asm
@@ -131,6 +131,7 @@ itoa:
 	push	rbp
 	mov	rbp, rsp
 
+	push	rbx
 	push	rsi
 	push	rdi
 	mov	rdi, rsi
@@ -176,6 +177,7 @@ itoa:
 
 	.quit:
 	pop	rax
+	pop	rbx
 	leave
 	ret
 ;----- exit(int exit_code) -----;