diff --git a/install-unix.xml.in b/install-unix.xml.in
index 359bdeacb..a445d072b 100644
--- a/install-unix.xml.in
+++ b/install-unix.xml.in
@@ -1,6 +1,5 @@
 <?xml version='1.0' encoding='UTF-8' ?>
-<!DOCTYPE set PUBLIC "-//OASIS//DTD DocBook XML V5.0//EN"
-"./docbook/docbook-xml/docbook.dtd" [
+<!DOCTYPE PHPDOC [
 
 <!ENTITY % language-defs     SYSTEM "../@LANGDIR@/language-defs.ent">
 <!ENTITY % language-snippets SYSTEM "../@LANGDIR@/language-snippets.ent">
@@ -21,7 +20,7 @@
 
 ]>
 
-<book xmlns="http://docbook.org/ns/docbook" version="5.0" xml:id="install" xml:lang="en" xmlns:xlink="http://www.w3.org/1999/xlink">
+<book xmlns="http://docbook.org/ns/docbook" version="5.2" xml:id="install" xml:lang="en" xmlns:xlink="http://www.w3.org/1999/xlink">
  <title>Installing PHP</title>
  <preface>
   <title>Preface</title>
diff --git a/install-win.xml.in b/install-win.xml.in
index 2a7c567b6..5d5d362d1 100644
--- a/install-win.xml.in
+++ b/install-win.xml.in
@@ -1,6 +1,5 @@
 <?xml version='1.0' encoding='UTF-8' ?>
-<!DOCTYPE set PUBLIC "-//OASIS//DTD DocBook XML V5.0//EN"
-"./docbook/docbook-xml/docbook.dtd" [
+<!DOCTYPE PHPDOC [
 
 <!ENTITY % language-defs     SYSTEM "../@LANGDIR@/language-defs.ent">
 <!ENTITY % language-snippets SYSTEM "../@LANGDIR@/language-snippets.ent">
@@ -26,7 +25,7 @@
      en/install/windows/index.xml file to build this file -->
 
 
-<book id="install" lang="en">
+<book xmlns="http://docbook.org/ns/docbook" version="5.2" xml:id="install" xml:lang="en">
 <title>Installation on Windows systems</title>
   <para>
   Installing PHP on modern Microsoft Windows systems and recommended configuration with common web servers.
diff --git a/manual.xml.in b/manual.xml.in
index 3fbc17a56..0d98ad202 100644
--- a/manual.xml.in
+++ b/manual.xml.in
@@ -1,9 +1,5 @@
 <?xml version='1.0' encoding='@ENCODING@' ?>
-<!DOCTYPE set PUBLIC "-//OASIS//DTD DocBook XML V5.0//EN"
-"./docbook/docbook-xml/docbook.dtd" [
-
-<!-- $Revision$ -->
-
+<!DOCTYPE PHPDOC [
 <!-- Add translated specific definitions and snippets -->
 @TRANSLATION_ONLY_INCL_BEGIN@
 <!ENTITY % language-defs     SYSTEM "../@LANGDIR@/language-defs.ent">
@@ -37,7 +33,7 @@
 %frontpage.entities;
 ]>
 
-<set xmlns="http://docbook.org/ns/docbook" version="5.0" xml:id="index" xml:lang="@LANG@" xmlns:xlink="http://www.w3.org/1999/xlink">
+<set xmlns="http://docbook.org/ns/docbook" version="5.2" xml:id="index" xml:lang="@LANG@" xmlns:xlink="http://www.w3.org/1999/xlink">
  <title>&PHPManual;</title>
  &bookinfo;