diff --git a/winsup/doc/ChangeLog b/winsup/doc/ChangeLog
index d8f31aafc..0677ae353 100644
--- a/winsup/doc/ChangeLog
+++ b/winsup/doc/ChangeLog
@@ -1,3 +1,11 @@
+2010-04-11  Christopher Faylor  <me+cygwin@cgf.cx>
+
+	* cygwin-api.in.sgml: Update to DocBook SGML 4.5 DTD.
+	* cygwin-ug-net.in.sgml: Ditto.
+	* cygwin-ug.in.sgml: Ditto.
+	* faq-sections.xml: Ditto.
+	* faq.xml: Ditto.
+
 2010-04-01  Charles Wilson  <cygwin@cwilson.fastmail.fm>
 
 	* setup-net.sgml: Remove more mentions of rxvt.
diff --git a/winsup/doc/cygwin-api.in.sgml b/winsup/doc/cygwin-api.in.sgml
index 2b5ec9d9c..15e663e97 100644
--- a/winsup/doc/cygwin-api.in.sgml
+++ b/winsup/doc/cygwin-api.in.sgml
@@ -1,6 +1,6 @@
 <?xml version="1.0"?>
-<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
-"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"[]>
+<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
+"http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" []>
 
 <book id="cygwin-api">
 
diff --git a/winsup/doc/cygwin-ug-net.in.sgml b/winsup/doc/cygwin-ug-net.in.sgml
index daab7ccb8..542457859 100644
--- a/winsup/doc/cygwin-ug-net.in.sgml
+++ b/winsup/doc/cygwin-ug-net.in.sgml
@@ -1,6 +1,6 @@
 <?xml version="1.0"?>
-<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
-"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"[]>
+<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
+"http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" []>
 
 <book id="cygwin-ug-net">
 
diff --git a/winsup/doc/cygwin-ug.in.sgml b/winsup/doc/cygwin-ug.in.sgml
index 65902e903..976f23f1c 100644
--- a/winsup/doc/cygwin-ug.in.sgml
+++ b/winsup/doc/cygwin-ug.in.sgml
@@ -1,5 +1,5 @@
 <?xml version="1.0"?>
-<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"[
+<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN" "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
   <!ENTITY cygnus-copyright "<year>1999,2000,2001,2002,2003,2004,2005,2006,2007,2008</year>
   <holder>Red Hat, Inc.</holder>">
   <!ENTITY cygnus-code-copyright "
diff --git a/winsup/doc/faq-sections.xml b/winsup/doc/faq-sections.xml
index a0bb7ac98..896a9661b 100644
--- a/winsup/doc/faq-sections.xml
+++ b/winsup/doc/faq-sections.xml
@@ -1,6 +1,6 @@
 <?xml version='1.0'?>
-<!DOCTYPE article PUBLIC '-//OASIS//DTD DocBook XML V4.2//EN'
-                      "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd" [
+<!DOCTYPE article PUBLIC '-//OASIS//DTD DocBook XML V4.5//EN'
+                      "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
       <!-- see http://www.unicode.org/charts/PDF/U0080.pdf -->
 	<!ENTITY pound      "&#x00A3;">
 	<!ENTITY brokenpipe "&#x00A6;">
diff --git a/winsup/doc/faq.xml b/winsup/doc/faq.xml
index 2db63d8ba..a48783410 100644
--- a/winsup/doc/faq.xml
+++ b/winsup/doc/faq.xml
@@ -1,6 +1,6 @@
 <?xml version='1.0'?>
-<!DOCTYPE article PUBLIC '-//OASIS//DTD DocBook XML V4.2//EN'
-                      "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd" [
+<!DOCTYPE article PUBLIC '-//OASIS//DTD DocBook XML V4.5//EN'
+                      "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
       <!-- see http://www.unicode.org/charts/PDF/U0080.pdf -->
 	<!ENTITY pound      "&#x00A3;">
 	<!ENTITY brokenpipe "&#x00A6;">