diff --git a/drivers/md/dm-writecache.c b/drivers/md/dm-writecache.c
index e672e1d17bf1d8fda5d632d41e7316ebb90a5d1e..3a28a68f184ca5baccaa541ad68fd60eade09df7 100644
--- a/drivers/md/dm-writecache.c
+++ b/drivers/md/dm-writecache.c
@@ -457,7 +457,7 @@ static void ssd_commit_flushed(struct dm_writecache *wc)
 		COMPLETION_INITIALIZER_ONSTACK(endio.c),
 		ATOMIC_INIT(1),
 	};
-	unsigned bitmap_bits = wc->dirty_bitmap_size * BITS_PER_LONG;
+	unsigned bitmap_bits = wc->dirty_bitmap_size * 8;
 	unsigned i = 0;
 
 	while (1) {