diff --git a/doc/datetime.txt b/doc/datetime.txt
index fc34b4bf..ef388f2b 100644
--- a/doc/datetime.txt
+++ b/doc/datetime.txt
@@ -2,6 +2,8 @@
 Date and time handling
 ======================
 
+This document describes the Duktape ``Date`` built-in implementation.
+
 Overview
 ========
 
diff --git a/doc/regexp.txt b/doc/regexp.txt
index cb6e29bd..3c2dba5d 100644
--- a/doc/regexp.txt
+++ b/doc/regexp.txt
@@ -2,6 +2,8 @@
 Regular expressions
 ===================
 
+This document describes the Duktape ``RegExp`` built-in implementation.
+
 Overview
 ========