diff --git a/code/os/11-syscall/plic.c b/code/os/11-syscall/plic.c
index c28a8d18064089cadb059c0f01b3e1429a127608..6dcf2f95218be377b3c9d9e979753ff5dd997d60 100644
--- a/code/os/11-syscall/plic.c
+++ b/code/os/11-syscall/plic.c
@@ -2,7 +2,7 @@
 
 void plic_init(void)
 {
-	int hart = r_tp();
+	int hart = r_mhartid();
   
 	/* 
 	 * Set priority for UART0.
@@ -56,7 +56,7 @@ void plic_init(void)
  */
 int plic_claim(void)
 {
-	int hart = r_tp();
+	int hart = r_mhartid();
 	int irq = *(uint32_t*)PLIC_MCLAIM(hart);
 	return irq;
 }
@@ -73,6 +73,6 @@ int plic_claim(void)
  */
 void plic_complete(int irq)
 {
-	int hart = r_tp();
+	int hart = r_mhartid();
 	*(uint32_t*)PLIC_MCOMPLETE(hart) = irq;
 }