diff --git a/sys/net/if.c b/sys/net/if.c
index 61575c895658..f7dbf476f5a0 100644
--- a/sys/net/if.c
+++ b/sys/net/if.c
@@ -217,7 +217,7 @@ netkqfilter(struct cdev *dev, struct knote *kn)
 		kn->kn_fop = &netdev_filtops;
 		break;
 	default:
-		return (1);
+		return (EINVAL);
 	}
 
 	idx = minor(dev);