diff --git a/fs/udf/super.c b/fs/udf/super.c
index cad2e15d633b..d75bfc733975 100644
--- a/fs/udf/super.c
+++ b/fs/udf/super.c
@@ -1418,7 +1418,8 @@ static int udf_load_sparable_map(struct super_block *sb,
 		if (ident != 0 ||
 		    strncmp(st->sparingIdent.ident, UDF_ID_SPARING,
 			    strlen(UDF_ID_SPARING)) ||
-		    sizeof(*st) + le16_to_cpu(st->reallocationTableLen) >
+		    struct_size(st, mapEntry,
+				le16_to_cpu(st->reallocationTableLen)) >
 							sb->s_blocksize) {
 			brelse(bh);
 			continue;