diff --git a/materials/chapter2/switch_case.S b/materials/chapter2/switch_case.S
index 4228a45..8174021 100644
--- a/materials/chapter2/switch_case.S
+++ b/materials/chapter2/switch_case.S
@@ -1,6 +1,6 @@
 st:
 	addi.w	$t0,$a0, -10	//a-10
-	sltiu	$t1,$t0, 8
+	sltui	$t1,$t0, 8
 	beqz	$t1, default	//if (a-10)>=8 
 							//goto default
 	la		$t2, jr_table
diff --git a/materials/chapter4/syscall_write.S b/materials/chapter4/syscall_write.S
index ef0f792..525e955 100644
--- a/materials/chapter4/syscall_write.S
+++ b/materials/chapter4/syscall_write.S
@@ -1,7 +1,7 @@
 .section .rodata                                                                
     .align 3
 .hello:
-	.ascii	"Hello World!\012\000"
+	.ascii	"Hello World!\n\000"
 
     .text
     .align 3