diff --git a/arch/um/drivers/line.c b/arch/um/drivers/line.c
index 46ceb25..6c2d4cc 100644
--- a/arch/um/drivers/line.c
+++ b/arch/um/drivers/line.c
@@ -714,7 +714,7 @@
 	struct tty_struct *tty;
 };
 
-irqreturn_t winch_interrupt(int irq, void *data, struct pt_regs *unused)
+static irqreturn_t winch_interrupt(int irq, void *data, struct pt_regs *unused)
 {
 	struct winch *winch = data;
 	struct tty_struct *tty;