diff --git a/doc/Clusters_from_Scratch/en-US/Preface.xml b/doc/Clusters_from_Scratch/en-US/Preface.xml
index 0e32108da6..678b160af3 100644
--- a/doc/Clusters_from_Scratch/en-US/Preface.xml
+++ b/doc/Clusters_from_Scratch/en-US/Preface.xml
@@ -1,13 +1,13 @@
 <?xml version='1.0' encoding='utf-8' ?>
 <!DOCTYPE preface PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN" "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
 <!ENTITY % BOOK_ENTITIES SYSTEM "Clusters_from_Scratch.ent">
 %BOOK_ENTITIES;
 ]>
-<preface>
-	<title>Preface</title>
-	<xi:include href="Common_Content/Conventions.xml" xmlns:xi="http://www.w3.org/2001/XInclude" />
-	<xi:include href="Feedback.xml" xmlns:xi="http://www.w3.org/2001/XInclude"><xi:fallback xmlns:xi="http://www.w3.org/2001/XInclude"><xi:include href="Common_Content/Feedback.xml" xmlns:xi="http://www.w3.org/2001/XInclude" />
-	</xi:fallback>
-	</xi:include>
+<preface><title>Preface</title>
+  <xi:include href="Common_Content/Conventions.xml" xmlns:xi="http://www.w3.org/2001/XInclude"/>
+  <xi:include href="Feedback.xml" xmlns:xi="http://www.w3.org/2001/XInclude">
+    <xi:fallback xmlns:xi="http://www.w3.org/2001/XInclude">
+      <xi:include href="Common_Content/Feedback.xml" xmlns:xi="http://www.w3.org/2001/XInclude"/>
+    </xi:fallback>
+  </xi:include>
 </preface>
-
diff --git a/doc/Pacemaker_Explained/en-US/Preface.xml b/doc/Pacemaker_Explained/en-US/Preface.xml
index eadd41d900..e63c4be5b2 100644
--- a/doc/Pacemaker_Explained/en-US/Preface.xml
+++ b/doc/Pacemaker_Explained/en-US/Preface.xml
@@ -1,11 +1,11 @@
 <?xml version='1.0' encoding='utf-8' ?>
-<!DOCTYPE Book PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN" "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
+<!DOCTYPE preface PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN" "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
 ]>
 <preface><title>Preface</title>
-  <xi:include href="Common_Content/Conventions.xml" xmlns:xi="http://www.w3.org/2001/XInclude"></xi:include>
+  <xi:include href="Common_Content/Conventions.xml" xmlns:xi="http://www.w3.org/2001/XInclude"/>
   <xi:include href="Feedback.xml" xmlns:xi="http://www.w3.org/2001/XInclude">
     <xi:fallback xmlns:xi="http://www.w3.org/2001/XInclude">
-      <xi:include href="Common_Content/Feedback.xml" xmlns:xi="http://www.w3.org/2001/XInclude"></xi:include>
+      <xi:include href="Common_Content/Feedback.xml" xmlns:xi="http://www.w3.org/2001/XInclude"/>
     </xi:fallback>
   </xi:include>
 </preface>