diff --git a/drivers/isdn/hardware/mISDN/hfcpci.c b/drivers/isdn/hardware/mISDN/hfcpci.c
index 7f910c76ca0a..3c92780bda09 100644
--- a/drivers/isdn/hardware/mISDN/hfcpci.c
+++ b/drivers/isdn/hardware/mISDN/hfcpci.c
@@ -2295,8 +2295,8 @@ _hfcpci_softirq(struct device *dev, void *arg)
 static void
 hfcpci_softirq(void *arg)
 {
-	(void) driver_for_each_device(&hfc_driver.driver, NULL, arg,
-				      _hfcpci_softirq);
+	WARN_ON_ONCE(driver_for_each_device(&hfc_driver.driver, NULL, arg,
+				      _hfcpci_softirq) != 0);
 
 	/* if next event would be in the past ... */
 	if ((s32)(hfc_jiffies + tics - jiffies) <= 0)