diff --git a/ext/.document b/ext/.document
index 31cfb4dee4..263d40444c 100644
--- a/ext/.document
+++ b/ext/.document
@@ -2,6 +2,8 @@
 
 enumerator/enumerator.c
 iconv/iconv.c
+nkf/lib/kconv.rb
+nkf/nkf.c
 stringio/stringio.c
 strscan/strscan.c
 zlib/zlib.c