diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index 1576b9d9a172..fec698d17d6a 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -3714,14 +3714,17 @@ static int build_sit_entries(struct f2fs_sb_info *sbi)
 			} else {
 				memcpy(se->discard_map, se->cur_valid_map,
 							SIT_VBLOCK_MAP_SIZE);
-				sbi->discard_blks += old_valid_blocks -
-							se->valid_blocks;
+				sbi->discard_blks += old_valid_blocks;
+				sbi->discard_blks -= se->valid_blocks;
 			}
 		}
 
-		if (sbi->segs_per_sec > 1)
+		if (sbi->segs_per_sec > 1) {
 			get_sec_entry(sbi, start)->valid_blocks +=
-				se->valid_blocks - old_valid_blocks;
+							se->valid_blocks;
+			get_sec_entry(sbi, start)->valid_blocks -=
+							old_valid_blocks;
+		}
 	}
 	up_read(&curseg->journal_rwsem);