diff --git a/fs/bcachefs/alloc_background.c b/fs/bcachefs/alloc_background.c
index bcfae91667af..ad256a88cb5c 100644
--- a/fs/bcachefs/alloc_background.c
+++ b/fs/bcachefs/alloc_background.c
@@ -319,6 +319,7 @@ void bch2_alloc_v4_swab(struct bkey_s k)
 	a->io_time[1]		= swab64(a->io_time[1]);
 	a->stripe		= swab32(a->stripe);
 	a->nr_external_backpointers = swab32(a->nr_external_backpointers);
+	a->fragmentation_lru	= swab64(a->fragmentation_lru);
 
 	bps = alloc_v4_backpointers(a);
 	for (bp = bps; bp < bps + BCH_ALLOC_V4_NR_BACKPOINTERS(a); bp++) {