diff --git a/fs/fat/fat_write.c b/fs/fat/fat_write.c
index cef138e..90d6ab6 100644
--- a/fs/fat/fat_write.c
+++ b/fs/fat/fat_write.c
@@ -882,7 +882,7 @@
 		}
 
 		curclust = get_fatent_value(mydata, dir_curclust);
-		if ((curclust >= 0xffffff8) || (curclust >= 0xfff8)) {
+		if (IS_LAST_CLUST(curclust, mydata->fatsize)) {
 			empty_dentptr = dentptr;
 			return NULL;
 		}