diff --git a/fs/ntfs3/bitmap.c b/fs/ntfs3/bitmap.c
index 5d44ceac855b..087282cb130b 100644
--- a/fs/ntfs3/bitmap.c
+++ b/fs/ntfs3/bitmap.c
@@ -1424,7 +1424,7 @@ int ntfs_trim_fs(struct ntfs_sb_info *sbi, struct fstrim_range *range)
 
 	down_read_nested(&wnd->rw_lock, BITMAP_MUTEX_CLUSTERS);
 
-	for (; iw < wnd->nbits; iw++, wbit = 0) {
+	for (; iw < wnd->nwnd; iw++, wbit = 0) {
 		CLST lcn_wnd = iw * wbits;
 		struct buffer_head *bh;