diff --git a/kernel/sched.c b/kernel/sched.c
index b4fbbc4..74dbb40 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -3355,7 +3355,7 @@
  * @p: the process that the cpu time gets accounted to
  * @cputime: the cpu time spent in virtual machine since the last update
  */
-void account_guest_time(struct task_struct *p, cputime_t cputime)
+static void account_guest_time(struct task_struct *p, cputime_t cputime)
 {
 	cputime64_t tmp;
 	struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat;