nnn.c | 1 +

diff --git a/nnn.c b/nnn.c
index 536a7f89314063ea845b13987919351243041a27..bf756c2389c9ad094a03c29c63403e1676e6eb31 100644
--- a/nnn.c
+++ b/nnn.c
@@ -3385,6 +3385,7 @@ 	while ((opt = getopt(argc, argv, "Slib:c:ep:vh")) != -1) {
 		switch (opt) {
 		case 'S':
 			cfg.blkorder = 1;
+			nftw_fn = sum_bsizes;
 			break;
 		case 'l':
 			cfg.showdetail = 0;