diff --git a/pkgs/tools/text/kdiff3/adjust-docbook-xml-version-to-4.2.patch b/pkgs/tools/text/kdiff3/adjust-docbook-xml-version-to-4.2.patch
new file mode 100644
index 000000000000..fdb96176abd3
--- /dev/null
+++ b/pkgs/tools/text/kdiff3/adjust-docbook-xml-version-to-4.2.patch
@@ -0,0 +1,45 @@
+The DocBook DTD must be 4.2 to validate with KDE 4.5.2.  In the upstream release 0.9.95
+of kdiff3 some languages have index.docbook with the 4.1.2 DTD.  This patch changes
+the version number in the DOCTYPE to 4.2 for these languages.
+
+
+diff -Naur kdiff3-upstream-0.9.95/doc/de/index.docbook kdiff3-0.9.95/doc/de/index.docbook
+--- kdiff3-upstream-0.9.95/doc/de/index.docbook	2010-10-18 22:38:40.043252907 -0430
++++ kdiff3-0.9.95/doc/de/index.docbook	2010-10-18 22:41:05.954329524 -0430
+@@ -1,5 +1,5 @@
+ <?xml version="1.0" ?>
+-<!DOCTYPE book PUBLIC "-//KDE//DTD DocBook XML V4.1.2-Based Variant V1.1//EN" "dtd/kdex.dtd" [
++<!DOCTYPE book PUBLIC "-//KDE//DTD DocBook XML V4.2-Based Variant V1.1//EN" "dtd/kdex.dtd" [
+   <!ENTITY kdiff3 "<application
+ >KDiff3</application
+ >">
+diff -Naur kdiff3-upstream-0.9.95/doc/fr/index.docbook kdiff3-0.9.95/doc/fr/index.docbook
+--- kdiff3-upstream-0.9.95/doc/fr/index.docbook	2010-10-18 22:38:40.043252907 -0430
++++ kdiff3-0.9.95/doc/fr/index.docbook	2010-10-18 22:41:05.965408604 -0430
+@@ -1,5 +1,5 @@
+ <?xml version="1.0" ?>
+-<!DOCTYPE book PUBLIC "-//KDE//DTD DocBook XML V4.1.2-Based Variant V1.1//EN" "dtd/kdex.dtd" [
++<!DOCTYPE book PUBLIC "-//KDE//DTD DocBook XML V4.2-Based Variant V1.1//EN" "dtd/kdex.dtd" [
+   <!ENTITY kdiff3 "<application
+ >KDiff3</application
+ >">
+diff -Naur kdiff3-upstream-0.9.95/doc/it/index.docbook kdiff3-0.9.95/doc/it/index.docbook
+--- kdiff3-upstream-0.9.95/doc/it/index.docbook	2010-10-18 22:38:40.044252773 -0430
++++ kdiff3-0.9.95/doc/it/index.docbook	2010-10-18 22:41:05.976408528 -0430
+@@ -1,5 +1,5 @@
+ <?xml version="1.0" ?>
+-<!DOCTYPE book PUBLIC "-//KDE//DTD DocBook XML V4.1.2-Based Variant V1.1//EN" "dtd/kdex.dtd" [
++<!DOCTYPE book PUBLIC "-//KDE//DTD DocBook XML V4.2-Based Variant V1.1//EN" "dtd/kdex.dtd" [
+   <!ENTITY kdiff3 "<application
+ >KDiff3</application
+ >">
+diff -Naur kdiff3-upstream-0.9.95/doc/nl/index.docbook kdiff3-0.9.95/doc/nl/index.docbook
+--- kdiff3-upstream-0.9.95/doc/nl/index.docbook	2010-10-18 22:38:40.043252907 -0430
++++ kdiff3-0.9.95/doc/nl/index.docbook	2010-10-18 22:41:05.986408860 -0430
+@@ -1,5 +1,5 @@
+ <?xml version="1.0" ?>
+-<!DOCTYPE book PUBLIC "-//KDE//DTD DocBook XML V4.1.2-Based Variant V1.1//EN" "dtd/kdex.dtd" [
++<!DOCTYPE book PUBLIC "-//KDE//DTD DocBook XML V4.2-Based Variant V1.1//EN" "dtd/kdex.dtd" [
+   <!ENTITY kdiff3 "<application
+ >KDiff3</application
+ >">
diff --git a/pkgs/tools/text/kdiff3/default.nix b/pkgs/tools/text/kdiff3/default.nix
index 05cd13c413b8..63956a630354 100644
--- a/pkgs/tools/text/kdiff3/default.nix
+++ b/pkgs/tools/text/kdiff3/default.nix
@@ -10,6 +10,9 @@ stdenv.mkDerivation rec {
   # kdebase allows having a konqueror plugin built
   buildInputs = [ cmake qt4 perl kdelibs automoc4 phonon gettext kdebase ];
 
+  # Adjust the version of the DocBook XML to 4.2 ( so that it validates ).
+  patches = [ ./adjust-docbook-xml-version-to-4.2.patch ];
+
   meta = {
     homepage = http://kdiff3.sourceforge.net/;
     license = "GPLv2+";