diff --git a/.rdoc_options b/.rdoc_options
index cc697cb862..51538b332d 100644
--- a/.rdoc_options
+++ b/.rdoc_options
@@ -1,3 +1,5 @@
 ---
 rdoc_include:
 - doc
+main_page: README.md
+op_dir: _site
diff --git a/ext/strscan/strscan.c b/ext/strscan/strscan.c
index 052a56e6ad..0d2155c612 100644
--- a/ext/strscan/strscan.c
+++ b/ext/strscan/strscan.c
@@ -2190,6 +2190,13 @@ strscan_named_captures(VALUE self)
                               Ruby Interface
    ======================================================================= */
 
+/*
+ * Document-class: StringScanner::Error
+ *
+ * The error class for StringScanner.
+ * See StringScanner#unscan.
+ */
+
 /*
  * Document-class: StringScanner
  *