diff --git a/drivers/target/target_core_user.c b/drivers/target/target_core_user.c
index d5477c0d730a343dc66ead69f30a479030922fa0..da187e635ea3f485ac8b69e6f414fa69313095ca 100644
--- a/drivers/target/target_core_user.c
+++ b/drivers/target/target_core_user.c
@@ -917,8 +917,10 @@ static int tcmu_configure_device(struct se_device *dev)
 	if (ret)
 		goto err_register;
 
+	/* User can set hw_block_size before enable the device */
+	if (dev->dev_attrib.hw_block_size == 0)
+		dev->dev_attrib.hw_block_size = 512;
 	/* Other attributes can be configured in userspace */
-	dev->dev_attrib.hw_block_size = 512;
 	dev->dev_attrib.hw_max_sectors = 128;
 	dev->dev_attrib.hw_queue_depth = 128;