diff --git a/arch/sandbox/board/clock.c b/arch/sandbox/board/clock.c
index 17409ec..27ae7e2 100644
--- a/arch/sandbox/board/clock.c
+++ b/arch/sandbox/board/clock.c
@@ -25,7 +25,7 @@
 #include <clock.h>
 #include <asm/arch/linux.h>
 
-uint64_t linux_clocksource_read(void)
+static uint64_t linux_clocksource_read(void)
 {
 	return linux_get_time();
 }