diff --git a/kernel/watchdog.c b/kernel/watchdog.c
index 613bc1f04610..b60e2a869bba 100644
--- a/kernel/watchdog.c
+++ b/kernel/watchdog.c
@@ -202,7 +202,7 @@ static struct perf_event_attr wd_hw_attr = {
 };
 
 /* Callback function for perf event subsystem */
-void watchdog_overflow_callback(struct perf_event *event, int nmi,
+static void watchdog_overflow_callback(struct perf_event *event, int nmi,
 		 struct perf_sample_data *data,
 		 struct pt_regs *regs)
 {