diff --git a/drivers/block/null_blk/main.c b/drivers/block/null_blk/main.c
index 4c8b4101516c..37172bb6efbd 100644
--- a/drivers/block/null_blk/main.c
+++ b/drivers/block/null_blk/main.c
@@ -1770,9 +1770,8 @@ static int null_validate_conf(struct nullb_device *dev)
 	if (dev->queue_mode == NULL_Q_BIO)
 		dev->mbps = 0;
 
-	if (dev->zoned &&
-	    (!dev->zone_size || !is_power_of_2(dev->zone_size))) {
-		pr_err("zone_size must be power-of-two\n");
+	if (dev->zoned && !dev->zone_size) {
+		pr_err("Invalid zero zone size\n");
 		return -EINVAL;
 	}
 
diff --git a/drivers/block/null_blk/null_blk.h b/drivers/block/null_blk/null_blk.h
index 64bef125d1df..277571c502d9 100644
--- a/drivers/block/null_blk/null_blk.h
+++ b/drivers/block/null_blk/null_blk.h
@@ -71,6 +71,7 @@ struct nullb_device {
 	unsigned int imp_close_zone_no;
 	struct nullb_zone *zones;
 	sector_t zone_size_sects;
+	unsigned int zone_size_sects_shift;
 	bool need_zone_res_mgmt;
 	spinlock_t zone_res_lock;
 
diff --git a/drivers/block/null_blk/zoned.c b/drivers/block/null_blk/zoned.c
index dae54dd1aeac..a8be1011def5 100644
--- a/drivers/block/null_blk/zoned.c
+++ b/drivers/block/null_blk/zoned.c
@@ -13,7 +13,10 @@ static inline sector_t mb_to_sects(unsigned long mb)
 
 static inline unsigned int null_zone_no(struct nullb_device *dev, sector_t sect)
 {
-	return sect >> ilog2(dev->zone_size_sects);
+	if (dev->zone_size_sects_shift)
+		return sect >> dev->zone_size_sects_shift;
+
+	return div64_u64(sect, dev->zone_size_sects);
 }
 
 static inline void null_lock_zone_res(struct nullb_device *dev)
@@ -62,10 +65,6 @@ int null_init_zoned_dev(struct nullb_device *dev, struct request_queue *q)
 	sector_t sector = 0;
 	unsigned int i;
 
-	if (!is_power_of_2(dev->zone_size)) {
-		pr_err("zone_size must be power-of-two\n");
-		return -EINVAL;
-	}
 	if (dev->zone_size > dev->size) {
 		pr_err("Zone size larger than device capacity\n");
 		return -EINVAL;
@@ -83,9 +82,14 @@ int null_init_zoned_dev(struct nullb_device *dev, struct request_queue *q)
 	zone_capacity_sects = mb_to_sects(dev->zone_capacity);
 	dev_capacity_sects = mb_to_sects(dev->size);
 	dev->zone_size_sects = mb_to_sects(dev->zone_size);
-	dev->nr_zones = round_up(dev_capacity_sects, dev->zone_size_sects)
-		>> ilog2(dev->zone_size_sects);
 
+	if (is_power_of_2(dev->zone_size_sects))
+		dev->zone_size_sects_shift = ilog2(dev->zone_size_sects);
+	else
+		dev->zone_size_sects_shift = 0;
+
+	dev->nr_zones =	DIV_ROUND_UP_SECTOR_T(dev_capacity_sects,
+					      dev->zone_size_sects);
 	dev->zones = kvmalloc_array(dev->nr_zones, sizeof(struct nullb_zone),
 				    GFP_KERNEL | __GFP_ZERO);
 	if (!dev->zones)