diff --git a/arch/s390/kernel/process.c b/arch/s390/kernel/process.c
index da6fbae..99182a41 100644
--- a/arch/s390/kernel/process.c
+++ b/arch/s390/kernel/process.c
@@ -103,7 +103,7 @@
 /*
  * The idle loop on a S390...
  */
-void default_idle(void)
+static void default_idle(void)
 {
 	int cpu, rc;