diff --git a/pixiv/filenames.go b/pixiv/filenames.go
index 8177ddc..52c4725 100644
--- a/pixiv/filenames.go
+++ b/pixiv/filenames.go
@@ -2,5 +2,5 @@ package pixiv
 
 const (
 	// should have subexpressions matching only for IDs
-	typicalFilenamesRegex = "(?:(?:illust_)(?P<illust_id_a>[0-9]*)(?:_[0-9]{8}_[0-9]{6}\\.(?:jpg|png|ugoira)))|(?:(?P<illust_id_b>[0-9]*)(?:_p[0-9]*\\.(?:jpg|png|ugoira)))"
+	typicalFilenamesRegex = "^(?:(?:illust_)(?P<illust_id_a>[0-9]*)(?:_[0-9]{8}_[0-9]{6}\\.(?:jpg|png|ugoira)))$|^(?:(?P<illust_id_b>[0-9]*)(?:_p[0-9]*\\.(?:jpg|png|ugoira)))$"
 )