diff --git a/string.asm b/string.asm
index 75df2c6..31f26e9 100644
--- a/string.asm
+++ b/string.asm
@@ -52,9 +52,13 @@ strcat:
 	push	rbp
 	mov	rbp, rsp
 
+	push	rdi
+	sub	rsp, 8
 	call	strlen
 	add	rdi, rax
 	call	strcpy
+	add	rsp, 8
+	pop	rax
 
 	leave
 	ret