diff --git a/sys/kern/subr_sglist.c b/sys/kern/subr_sglist.c
--- a/sys/kern/subr_sglist.c
+++ b/sys/kern/subr_sglist.c
@@ -386,7 +386,8 @@
 	struct iovec *iov;
 	size_t done;
 	pmap_t pmap;
-	int error, len;
+	int error;
+	size_t len;
 
 	if (sg->sg_maxseg == 0)
 		return (EINVAL);