diff --git a/drivers/isdn/hisax/isurf.c b/drivers/isdn/hisax/isurf.c
index 1399ddd4f6cb..53e299be4304 100644
--- a/drivers/isdn/hisax/isurf.c
+++ b/drivers/isdn/hisax/isurf.c
@@ -238,7 +238,7 @@ int setup_isurf(struct IsdnCard *card)
 				cs->hw.isurf.reset = pnp_port_start(pnp_d, 0);
 				cs->hw.isurf.phymem = pnp_mem_start(pnp_d, 1);
 				cs->irq = pnp_irq(pnp_d, 0);
-				if (!cs->irq || !cs->hw.isurf.reset || !cs->hw.isurf.phymem) {
+				if (cs->irq == -1 || !cs->hw.isurf.reset || !cs->hw.isurf.phymem) {
 					printk(KERN_ERR "ISurfPnP:some resources are missing %d/%x/%lx\n",
 					       cs->irq, cs->hw.isurf.reset, cs->hw.isurf.phymem);
 					pnp_disable_dev(pnp_d);