diff --git a/drivers/lightnvm/pblk-init.c b/drivers/lightnvm/pblk-init.c
index 145922589b0c659f9b69869e79309a86ab316c40..dc32274881b2fae0a755719ea0f4bb2e08f45d2d 100644
--- a/drivers/lightnvm/pblk-init.c
+++ b/drivers/lightnvm/pblk-init.c
@@ -181,7 +181,8 @@ static int pblk_rwb_init(struct pblk *pblk)
 	unsigned int power_size, power_seg_sz;
 	int pgs_in_buffer;
 
-	pgs_in_buffer = max(geo->mw_cunits, geo->ws_opt) * geo->all_luns;
+	pgs_in_buffer = (max(geo->mw_cunits, geo->ws_opt) + geo->ws_opt)
+								* geo->all_luns;
 
 	if (write_buffer_size && (write_buffer_size > pgs_in_buffer))
 		buffer_size = write_buffer_size;