diff --git a/drivers/isdn/i4l/isdn_common.c b/drivers/isdn/i4l/isdn_common.c
index 38a5bb764c7b..598724ffde4e 100644
--- a/drivers/isdn/i4l/isdn_common.c
+++ b/drivers/isdn/i4l/isdn_common.c
@@ -1640,13 +1640,7 @@ isdn_ioctl(struct file *file, uint cmd, ulong arg)
 			} else
 				return -EINVAL;
 		case IIOCDBGVAR:
-			if (arg) {
-				if (copy_to_user(argp, &dev, sizeof(ulong)))
-					return -EFAULT;
-				return 0;
-			} else
-				return -EINVAL;
-			break;
+			return -EINVAL;
 		default:
 			if ((cmd & IIOCDRVCTL) == IIOCDRVCTL)
 				cmd = ((cmd >> _IOC_NRSHIFT) & _IOC_NRMASK) & ISDN_DRVIOCTL_MASK;