diff -u -r --new-file iputils-s20190324/doc/arping.xml iputils-s20190515/doc/arping.xml
--- iputils-s20190324/doc/arping.xml	2019-03-24 09:28:37.000000000 -0500
+++ iputils-s20190515/doc/arping.xml	2019-05-15 15:14:10.000000000 -0500
@@ -1,4 +1,4 @@
-<refentry xmlns:db="http://docbook.org/ns/docbook" version="5.0"
+<refentry xmlns="http://docbook.org/ns/docbook" version="5.0"
 xml:id="man.arping">
 
   <refentryinfo>
diff -u -r --new-file iputils-s20190324/doc/clockdiff.xml iputils-s20190515/doc/clockdiff.xml
--- iputils-s20190324/doc/clockdiff.xml	2019-03-24 09:28:37.000000000 -0500
+++ iputils-s20190515/doc/clockdiff.xml	2019-05-15 15:14:10.000000000 -0500
@@ -1,4 +1,4 @@
-<refentry xmlns:db="http://docbook.org/ns/docbook" version="5.0"
+<refentry xmlns="http://docbook.org/ns/docbook" version="5.0"
 xml:id="man.clockdiff">
 
   <refentryinfo>
diff -u -r --new-file iputils-s20190324/doc/custom-html.xsl iputils-s20190515/doc/custom-html.xsl
--- iputils-s20190324/doc/custom-html.xsl	2019-03-24 09:28:37.000000000 -0500
+++ iputils-s20190515/doc/custom-html.xsl	2019-05-15 15:14:10.000000000 -0500
@@ -2,7 +2,7 @@
 
 <xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0">
 
-<xsl:import href="http://docbook.sourceforge.net/release/xsl/current/html/docbook.xsl"/>
+<xsl:import href="http://docbook.sourceforge.net/release/xsl-ns/current/html/docbook.xsl"/>
 <!--
   - The docbook stylesheet injects empty anchor tags into generated HTML, identified by an auto-generated ID.
   - Ask the docbook stylesheet to generate reproducible output when generating (these) ID values.
diff -u -r --new-file iputils-s20190324/doc/custom-man.xsl iputils-s20190515/doc/custom-man.xsl
--- iputils-s20190324/doc/custom-man.xsl	2019-03-24 09:28:37.000000000 -0500
+++ iputils-s20190515/doc/custom-man.xsl	2019-05-15 15:14:10.000000000 -0500
@@ -5,7 +5,7 @@
                 extension-element-prefixes="exsl"
                 version="1.0">
 
-<xsl:import href="http://docbook.sourceforge.net/release/xsl/current/manpages/docbook.xsl"/>
+<xsl:import href="http://docbook.sourceforge.net/release/xsl-ns/current/manpages/docbook.xsl"/>
 
 <xsl:template name="top.comment" />
 
diff -u -r --new-file iputils-s20190324/doc/meson.build iputils-s20190515/doc/meson.build
--- iputils-s20190324/doc/meson.build	2019-03-24 09:28:37.000000000 -0500
+++ iputils-s20190515/doc/meson.build	2019-05-15 15:14:10.000000000 -0500
@@ -38,7 +38,7 @@
 	manpages += ['ninfod']
 endif
 
-xsltproc = find_program('xsltproc', required : false)
+xsltproc = find_program('xsltproc', required : true)
 xsltproc_args = [
 	'--nonet',
 	'--stringparam', 'man.output.quietly', '1',
@@ -48,15 +48,22 @@
 ]
 
 if xsltproc.found()
-	testrun = run_command([xsltproc, '--nonet',
-		'http://docbook.sourceforge.net/release/xsl/current/manpages/docbook.xsl'])
+	xsl = 'http://docbook.sourceforge.net/release/xsl/current/manpages/docbook.xsl'
+	testrun = run_command([xsltproc, '--nonet', xsl])
 	xsltproc_works = testrun.returncode() == 0
+	if xsltproc_works == false
+		warning('xsltproc: cannot process ' + xsl)
+	endif
 else
 	warning('No docbook stylesheet found for generating man pages')
 	xsltproc_works = false
 endif
 
-if build_mans and xsltproc_works
+if xsltproc_works == false
+	error('Man pages cannot be built: xsltproc does not work correctly')
+endif
+
+if build_mans
 	foreach man : manpages
 		custom_target(man + '.8',
 			output : man + '.8',
@@ -74,7 +81,7 @@
 	endforeach
 endif
 
-if build_html_mans and xsltproc_works
+if build_html_mans
 	foreach man : manpages
 		custom_target(man + '.html',
 			output : man + '.html',
diff -u -r --new-file iputils-s20190324/doc/ninfod.xml iputils-s20190515/doc/ninfod.xml
--- iputils-s20190324/doc/ninfod.xml	2019-03-24 09:28:37.000000000 -0500
+++ iputils-s20190515/doc/ninfod.xml	2019-05-15 15:14:10.000000000 -0500
@@ -1,4 +1,4 @@
-<refentry xmlns:db="http://docbook.org/ns/docbook" version="5.0"
+<refentry xmlns="http://docbook.org/ns/docbook" version="5.0"
 xml:id="man.ninfod">
 
   <refentryinfo>
diff -u -r --new-file iputils-s20190324/doc/ping.xml iputils-s20190515/doc/ping.xml
--- iputils-s20190324/doc/ping.xml	2019-03-24 09:28:37.000000000 -0500
+++ iputils-s20190515/doc/ping.xml	2019-05-15 15:14:10.000000000 -0500
@@ -1,4 +1,4 @@
-<refentry xmlns:db="http://docbook.org/ns/docbook" version="5.0"
+<refentry xmlns="http://docbook.org/ns/docbook" version="5.0"
 xml:id="man.ping">
 
   <refentryinfo>
diff -u -r --new-file iputils-s20190324/doc/rarpd.xml iputils-s20190515/doc/rarpd.xml
--- iputils-s20190324/doc/rarpd.xml	2019-03-24 09:28:37.000000000 -0500
+++ iputils-s20190515/doc/rarpd.xml	2019-05-15 15:14:10.000000000 -0500
@@ -1,4 +1,4 @@
-<refentry xmlns:db="http://docbook.org/ns/docbook" version="5.0"
+<refentry xmlns="http://docbook.org/ns/docbook" version="5.0"
 xml:id="man.rarpd">
 
   <refentryinfo>
diff -u -r --new-file iputils-s20190324/doc/rdisc.xml iputils-s20190515/doc/rdisc.xml
--- iputils-s20190324/doc/rdisc.xml	2019-03-24 09:28:37.000000000 -0500
+++ iputils-s20190515/doc/rdisc.xml	2019-05-15 15:14:10.000000000 -0500
@@ -1,4 +1,4 @@
-<refentry xmlns:db="http://docbook.org/ns/docbook" version="5.0"
+<refentry xmlns="http://docbook.org/ns/docbook" version="5.0"
 xml:id="man.rdisc">
 
   <refentryinfo>
diff -u -r --new-file iputils-s20190324/doc/tftpd.xml iputils-s20190515/doc/tftpd.xml
--- iputils-s20190324/doc/tftpd.xml	2019-03-24 09:28:37.000000000 -0500
+++ iputils-s20190515/doc/tftpd.xml	2019-05-15 15:14:10.000000000 -0500
@@ -1,4 +1,4 @@
-<refentry xmlns:db="http://docbook.org/ns/docbook" version="5.0"
+<refentry xmlns="http://docbook.org/ns/docbook" version="5.0"
 xml:id="man.tftpd">
 
   <refentryinfo>
diff -u -r --new-file iputils-s20190324/doc/tracepath.xml iputils-s20190515/doc/tracepath.xml
--- iputils-s20190324/doc/tracepath.xml	2019-03-24 09:28:37.000000000 -0500
+++ iputils-s20190515/doc/tracepath.xml	2019-05-15 15:14:10.000000000 -0500
@@ -1,4 +1,4 @@
-<refentry xmlns:db="http://docbook.org/ns/docbook" version="5.0"
+<refentry xmlns="http://docbook.org/ns/docbook" version="5.0"
 xml:id="man.tracepath">
 
   <refentryinfo>
diff -u -r --new-file iputils-s20190324/doc/traceroute6.xml iputils-s20190515/doc/traceroute6.xml
--- iputils-s20190324/doc/traceroute6.xml	2019-03-24 09:28:37.000000000 -0500
+++ iputils-s20190515/doc/traceroute6.xml	2019-05-15 15:14:10.000000000 -0500
@@ -1,4 +1,4 @@
-<refentry xmlns:db="http://docbook.org/ns/docbook" version="5.0"
+<refentry xmlns="http://docbook.org/ns/docbook" version="5.0"
 xml:id="man.traceroute6">
 
   <refentryinfo>
diff -u -r --new-file iputils-s20190324/meson.build iputils-s20190515/meson.build
--- iputils-s20190324/meson.build	2019-03-24 09:28:37.000000000 -0500
+++ iputils-s20190515/meson.build	2019-05-15 15:14:10.000000000 -0500
@@ -3,7 +3,7 @@
 		'c_std=c99',
 		'warning_level=3',
 	],
-	version : 's20190324') # keep in sync with: git describe | awk -F- '{print $1}'
+	version : 's20190515') # keep in sync with: git describe | awk -F- '{print $1}'
 
 cc = meson.get_compiler('c')