diff --git a/lib/proc.c b/lib/proc.c
index 73aec31..a55c8d6 100644
--- a/lib/proc.c
+++ b/lib/proc.c
@@ -5,4 +5,4 @@ struct Cpu cpus[NCPU];
 /**
  * Return this CPU's cpu struct. Interrupts must be disabled.
  */
-inline struct Cpu *mycpu(void) { return &cpus[r_tp()]; }
+inline struct Cpu *mycpu(void) { return &cpus[read_tp()]; }