diff --git a/doc/.document b/doc/.document
index ad17aada6d..f35cd4769b 100644
--- a/doc/.document
+++ b/doc/.document
@@ -2,3 +2,4 @@
 *.rdoc
 NEWS-*
 syntax
+optparse
diff --git a/doc/optparse/.document b/doc/optparse/.document
new file mode 100644
index 0000000000..96dfc7779f
--- /dev/null
+++ b/doc/optparse/.document
@@ -0,0 +1 @@
+*.rdoc