diff --git a/stand/libsa/zfs/zfs.c b/stand/libsa/zfs/zfs.c
--- a/stand/libsa/zfs/zfs.c
+++ b/stand/libsa/zfs/zfs.c
@@ -827,27 +827,12 @@
 int
 zfs_get_bootonce(void *vdev, const char *key, char *buf, size_t size)
 {
-	nvlist_t *benv;
-	char *result = NULL;
-	int result_size, rv;
-
-	if ((rv = zfs_get_bootenv(vdev, &benv)) != 0)
-		return (rv);
+	spa_t *spa;
 
-	if ((rv = nvlist_find(benv, key, DATA_TYPE_STRING, NULL,
-	    &result, &result_size)) == 0) {
-		if (result_size == 0) {
-			/* ignore empty string */
-			rv = ENOENT;
-		} else {
-			size = MIN((size_t)result_size + 1, size);
-			strlcpy(buf, result, size);
-		}
-		(void) nvlist_remove(benv, key, DATA_TYPE_STRING);
-		(void) zfs_set_bootenv(vdev, benv);
-	}
+	if ((spa = spa_find_by_dev((struct zfs_devdesc *)vdev)) == NULL)
+		return (ENXIO);
 
-	return (rv);
+	return (zfs_get_bootonce_spa(spa, key, buf, size));
 }
 
 /*
diff --git a/stand/libsa/zfs/zfsimpl.c b/stand/libsa/zfs/zfsimpl.c
--- a/stand/libsa/zfs/zfsimpl.c
+++ b/stand/libsa/zfs/zfsimpl.c
@@ -3899,3 +3899,36 @@
 	spa->spa_bootenv = benv;
 	return (0);
 }
+
+/*
+ * Get bootonce value by key. The bootonce <key, value> pair is removed from the
+ * bootenv nvlist and the remaining nvlist is committed back to disk. This process
+ * the bootonce flag since we've reached the point in the boot that we've 'used'
+ * the BE. For chained boot scenarios, we may reach this point multiple times (but
+ * only remove it and return 0 the first time).
+ */
+static int
+zfs_get_bootonce_spa(spa_t *spa, const char *key, char *buf, size_t size)
+{
+	nvlist_t *benv;
+	char *result = NULL;
+	int result_size, rv;
+
+	if ((rv = zfs_get_bootenv_spa(spa, &benv)) != 0)
+		return (rv);
+
+	if ((rv = nvlist_find(benv, key, DATA_TYPE_STRING, NULL,
+	    &result, &result_size)) == 0) {
+		if (result_size == 0) {
+			/* ignore empty string */
+			rv = ENOENT;
+		} else if (buf != NULL) {
+			size = MIN((size_t)result_size + 1, size);
+			strlcpy(buf, result, size);
+		}
+		(void)nvlist_remove(benv, key, DATA_TYPE_STRING);
+		(void)zfs_set_bootenv_spa(spa, benv);
+	}
+
+	return (rv);
+}