diff --git a/sys/vm/vm_domainset.c b/sys/vm/vm_domainset.c
--- a/sys/vm/vm_domainset.c
+++ b/sys/vm/vm_domainset.c
@@ -104,7 +104,7 @@
 
 	/* Grab the next domain in 'ds_order'. */
 	*domain = di->di_domain->ds_order[
-	    (*di->di_iter)++ % di->di_domain->ds_cnt];
+	    atomic_fetchadd_int(di->di_iter, 1) % di->di_domain->ds_cnt];
 }
 
 static void
@@ -113,7 +113,6 @@
 	int d;
 
 	d = di->di_offset % di->di_domain->ds_cnt;
-	*di->di_iter = d;
 	*domain = di->di_domain->ds_order[d];
 }