diff --git a/module/zfs/vdev.c b/module/zfs/vdev.c
index 92b9958940..cb4a3e2524 100644
--- a/module/zfs/vdev.c
+++ b/module/zfs/vdev.c
@@ -1021,13 +1021,14 @@ vdev_open_children(vdev_t *vd)
 {
 	taskq_t *tq;
 	int children = vd->vdev_children;
+	int c;
 
 	tq = taskq_create("vdev_open", children, minclsyspri,
 	    children, children, TASKQ_PREPOPULATE);
 
-	for (int c = 0; c < children; c++)
+	for (c = 0; c < children; c++)
 		VERIFY(taskq_dispatch(tq, vdev_open_child, vd->vdev_child[c],
-		    TQ_SLEEP) != NULL);
+		    TQ_SLEEP) != 0);
 
 	taskq_destroy(tq);
 }
diff --git a/module/zfs/vdev_mirror.c b/module/zfs/vdev_mirror.c
index 58e3a53288..32615c0bc3 100644
--- a/module/zfs/vdev_mirror.c
+++ b/module/zfs/vdev_mirror.c
@@ -126,6 +126,7 @@ vdev_mirror_open(vdev_t *vd, uint64_t *asize, uint64_t *ashift)
 {
 	int numerrors = 0;
 	int lasterror = 0;
+	int c;
 
 	if (vd->vdev_children == 0) {
 		vd->vdev_stat.vs_aux = VDEV_AUX_BAD_LABEL;
@@ -134,7 +135,7 @@ vdev_mirror_open(vdev_t *vd, uint64_t *asize, uint64_t *ashift)
 
 	vdev_open_children(vd);
 
-	for (int c = 0; c < vd->vdev_children; c++) {
+	for (c = 0; c < vd->vdev_children; c++) {
 		vdev_t *cvd = vd->vdev_child[c];
 
 		if (cvd->vdev_open_error) {
@@ -158,7 +159,9 @@ vdev_mirror_open(vdev_t *vd, uint64_t *asize, uint64_t *ashift)
 static void
 vdev_mirror_close(vdev_t *vd)
 {
-	for (int c = 0; c < vd->vdev_children; c++)
+	int c;
+
+	for (c = 0; c < vd->vdev_children; c++)
 		vdev_close(vd->vdev_child[c]);
 }
 
diff --git a/module/zfs/vdev_root.c b/module/zfs/vdev_root.c
index 524c8e6060..dc9c0b9845 100644
--- a/module/zfs/vdev_root.c
+++ b/module/zfs/vdev_root.c
@@ -54,6 +54,7 @@ vdev_root_open(vdev_t *vd, uint64_t *asize, uint64_t *ashift)
 {
 	int lasterror = 0;
 	int numerrors = 0;
+	int c;
 
 	if (vd->vdev_children == 0) {
 		vd->vdev_stat.vs_aux = VDEV_AUX_BAD_LABEL;
@@ -62,7 +63,7 @@ vdev_root_open(vdev_t *vd, uint64_t *asize, uint64_t *ashift)
 
 	vdev_open_children(vd);
 
-	for (int c = 0; c < vd->vdev_children; c++) {
+	for (c = 0; c < vd->vdev_children; c++) {
 		vdev_t *cvd = vd->vdev_child[c];
 
 		if (cvd->vdev_open_error && !cvd->vdev_islog) {
@@ -85,7 +86,9 @@ vdev_root_open(vdev_t *vd, uint64_t *asize, uint64_t *ashift)
 static void
 vdev_root_close(vdev_t *vd)
 {
-	for (int c = 0; c < vd->vdev_children; c++)
+	int c;
+
+	for (c = 0; c < vd->vdev_children; c++)
 		vdev_close(vd->vdev_child[c]);
 }