diff --git a/man/file-hierarchy.xml b/man/file-hierarchy.xml
index 5c9b76674c..4e5eeda9e5 100644
--- a/man/file-hierarchy.xml
+++ b/man/file-hierarchy.xml
@@ -3,7 +3,7 @@
   "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
 <!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
 
-<refentry id="file-hierarchy">
+<refentry id="file-hierarchy" xmlns:xi="http://www.w3.org/2001/XInclude">
 
   <refentryinfo>
     <title>file-hierarchy</title>
diff --git a/man/kernel-command-line.xml b/man/kernel-command-line.xml
index 43247fe534..d15b4bf3fc 100644
--- a/man/kernel-command-line.xml
+++ b/man/kernel-command-line.xml
@@ -3,7 +3,7 @@
   "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
 <!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
 
-<refentry id="kernel-command-line">
+<refentry id="kernel-command-line" xmlns:xi="http://www.w3.org/2001/XInclude">
 
   <refentryinfo>
     <title>kernel-command-line</title>
diff --git a/man/machine-info.xml b/man/machine-info.xml
index 781208b600..bae5e4beb3 100644
--- a/man/machine-info.xml
+++ b/man/machine-info.xml
@@ -3,7 +3,7 @@
   "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
 <!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
 
-<refentry id="machine-info">
+<refentry id="machine-info" xmlns:xi="http://www.w3.org/2001/XInclude">
   <refentryinfo>
     <title>machine-info</title>
     <productname>systemd</productname>
diff --git a/man/nss-resolve.xml b/man/nss-resolve.xml
index 9954d4082f..49d67dd21b 100644
--- a/man/nss-resolve.xml
+++ b/man/nss-resolve.xml
@@ -3,7 +3,8 @@
   "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
 <!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
 
-<refentry id="nss-resolve" conditional='ENABLE_NSS_RESOLVE'>
+<refentry id="nss-resolve" conditional='ENABLE_NSS_RESOLVE'
+          xmlns:xi="http://www.w3.org/2001/XInclude">
 
   <refentryinfo>
     <title>nss-resolve</title>
diff --git a/man/pam_systemd.xml b/man/pam_systemd.xml
index f2bd3de0b0..c430e7dd51 100644
--- a/man/pam_systemd.xml
+++ b/man/pam_systemd.xml
@@ -3,7 +3,7 @@
   "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
 <!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
 
-<refentry id="pam_systemd" conditional='HAVE_PAM'>
+<refentry id="pam_systemd" conditional='HAVE_PAM' xmlns:xi="http://www.w3.org/2001/XInclude">
 
   <refentryinfo>
     <title>pam_systemd</title>
diff --git a/man/pam_systemd_home.xml b/man/pam_systemd_home.xml
index 9d07aa96c7..489dde8711 100644
--- a/man/pam_systemd_home.xml
+++ b/man/pam_systemd_home.xml
@@ -3,7 +3,8 @@
   "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
 <!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
 
-<refentry id="pam_systemd_home" conditional='ENABLE_PAM_HOME'>
+<refentry id="pam_systemd_home" conditional='ENABLE_PAM_HOME'
+          xmlns:xi="http://www.w3.org/2001/XInclude">
 
   <refentryinfo>
     <title>pam_systemd_home</title>
diff --git a/man/sd_bus_message_read_strv.xml b/man/sd_bus_message_read_strv.xml
index 6f46c18e09..f034d02d8a 100644
--- a/man/sd_bus_message_read_strv.xml
+++ b/man/sd_bus_message_read_strv.xml
@@ -3,7 +3,7 @@
   "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
 <!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
 
-<refentry id="sd_bus_message_read_strv">
+<refentry id="sd_bus_message_read_strv" xmlns:xi="http://www.w3.org/2001/XInclude">
 
   <refentryinfo>
     <title>sd_bus_message_read_strv</title>
diff --git a/man/smbios-type-11.xml b/man/smbios-type-11.xml
index 5b8b32b0e9..c95dc741c9 100644
--- a/man/smbios-type-11.xml
+++ b/man/smbios-type-11.xml
@@ -3,7 +3,7 @@
   "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
 <!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
 
-<refentry id="smbios-type-11">
+<refentry id="smbios-type-11" xmlns:xi="http://www.w3.org/2001/XInclude">
 
   <refentryinfo>
     <title>smbios-type-11</title>
diff --git a/man/systemd-backlight@.service.xml b/man/systemd-backlight@.service.xml
index 7294910ca3..85609949ff 100644
--- a/man/systemd-backlight@.service.xml
+++ b/man/systemd-backlight@.service.xml
@@ -3,7 +3,8 @@
 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
   "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
 <!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
-<refentry id="systemd-backlight@.service" conditional='ENABLE_BACKLIGHT'>
+<refentry id="systemd-backlight@.service" conditional='ENABLE_BACKLIGHT'
+          xmlns:xi="http://www.w3.org/2001/XInclude">
 
   <refentryinfo>
     <title>systemd-backlight@.service</title>
diff --git a/man/systemd-cryptsetup-generator.xml b/man/systemd-cryptsetup-generator.xml
index e539625d6e..b803c268df 100644
--- a/man/systemd-cryptsetup-generator.xml
+++ b/man/systemd-cryptsetup-generator.xml
@@ -3,7 +3,8 @@
 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
   "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
 <!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
-<refentry id="systemd-cryptsetup-generator" conditional='HAVE_LIBCRYPTSETUP'>
+<refentry id="systemd-cryptsetup-generator" conditional='HAVE_LIBCRYPTSETUP'
+          xmlns:xi="http://www.w3.org/2001/XInclude">
 
   <refentryinfo>
     <title>systemd-cryptsetup-generator</title>
diff --git a/man/systemd-fsck@.service.xml b/man/systemd-fsck@.service.xml
index 45104bb12a..5eaef91009 100644
--- a/man/systemd-fsck@.service.xml
+++ b/man/systemd-fsck@.service.xml
@@ -3,7 +3,7 @@
 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
   "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
 <!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
-<refentry id="systemd-fsck@.service">
+<refentry id="systemd-fsck@.service" xmlns:xi="http://www.w3.org/2001/XInclude">
 
   <refentryinfo>
     <title>systemd-fsck@.service</title>
diff --git a/man/systemd-fstab-generator.xml b/man/systemd-fstab-generator.xml
index 9173970bf7..a1174530a0 100644
--- a/man/systemd-fstab-generator.xml
+++ b/man/systemd-fstab-generator.xml
@@ -3,7 +3,7 @@
 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
   "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
 <!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
-<refentry id="systemd-fstab-generator">
+<refentry id="systemd-fstab-generator" xmlns:xi="http://www.w3.org/2001/XInclude">
 
   <refentryinfo>
     <title>systemd-fstab-generator</title>
diff --git a/man/systemd-getty-generator.xml b/man/systemd-getty-generator.xml
index d2e05dc82f..3728b7f5e7 100644
--- a/man/systemd-getty-generator.xml
+++ b/man/systemd-getty-generator.xml
@@ -3,7 +3,7 @@
 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
   "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
 <!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
-<refentry id="systemd-getty-generator">
+<refentry id="systemd-getty-generator" xmlns:xi="http://www.w3.org/2001/XInclude">
 
   <refentryinfo>
     <title>systemd-getty-generator</title>
diff --git a/man/systemd-gpt-auto-generator.xml b/man/systemd-gpt-auto-generator.xml
index 7f4a7325db..69620feff4 100644
--- a/man/systemd-gpt-auto-generator.xml
+++ b/man/systemd-gpt-auto-generator.xml
@@ -3,7 +3,8 @@
   "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
 <!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
 
-<refentry id="systemd-gpt-auto-generator" conditional='HAVE_BLKID'>
+<refentry id="systemd-gpt-auto-generator" conditional='HAVE_BLKID'
+          xmlns:xi="http://www.w3.org/2001/XInclude">
 
   <refentryinfo>
     <title>systemd-gpt-auto-generator</title>
diff --git a/man/systemd-hibernate-resume-generator.xml b/man/systemd-hibernate-resume-generator.xml
index 539b92cb3a..8bc61c7dfb 100644
--- a/man/systemd-hibernate-resume-generator.xml
+++ b/man/systemd-hibernate-resume-generator.xml
@@ -3,7 +3,8 @@
 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
   "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
 <!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
-<refentry id="systemd-hibernate-resume-generator" conditional='ENABLE_HIBERNATE'>
+<refentry id="systemd-hibernate-resume-generator" conditional='ENABLE_HIBERNATE'
+          xmlns:xi="http://www.w3.org/2001/XInclude">
 
   <refentryinfo>
     <title>systemd-hibernate-resume-generator</title>
diff --git a/man/systemd-homed.service.xml b/man/systemd-homed.service.xml
index 2bc1dba375..9564cec6f5 100644
--- a/man/systemd-homed.service.xml
+++ b/man/systemd-homed.service.xml
@@ -3,7 +3,8 @@
   "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
 <!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
 
-<refentry id="systemd-homed.service" conditional='ENABLE_HOMED'>
+<refentry id="systemd-homed.service" conditional='ENABLE_HOMED'
+          xmlns:xi="http://www.w3.org/2001/XInclude">
 
   <refentryinfo>
     <title>systemd-homed.service</title>
diff --git a/man/systemd-integritysetup@.service.xml b/man/systemd-integritysetup@.service.xml
index 3dca2c3b44..8906511aff 100644
--- a/man/systemd-integritysetup@.service.xml
+++ b/man/systemd-integritysetup@.service.xml
@@ -3,7 +3,8 @@
 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
   "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
 <!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
-<refentry id="systemd-integritysetup@.service" conditional='HAVE_LIBCRYPTSETUP'>
+<refentry id="systemd-integritysetup@.service" conditional='HAVE_LIBCRYPTSETUP'
+          xmlns:xi="http://www.w3.org/2001/XInclude">
 
   <refentryinfo>
     <title>systemd-integritysetup@.service</title>
diff --git a/man/systemd-journald.service.xml b/man/systemd-journald.service.xml
index 6b0fb3137c..55e7d1669a 100644
--- a/man/systemd-journald.service.xml
+++ b/man/systemd-journald.service.xml
@@ -3,7 +3,8 @@
   "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
 <!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
 
-<refentry id="systemd-journald.service">
+<refentry id="systemd-journald.service"
+          xmlns:xi="http://www.w3.org/2001/XInclude">
 
   <refentryinfo>
     <title>systemd-journald.service</title>
diff --git a/man/systemd-modules-load.service.xml b/man/systemd-modules-load.service.xml
index 691194866a..69b9629c10 100644
--- a/man/systemd-modules-load.service.xml
+++ b/man/systemd-modules-load.service.xml
@@ -3,7 +3,8 @@
 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
   "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
 <!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
-<refentry id="systemd-modules-load.service" conditional='HAVE_KMOD'>
+<refentry id="systemd-modules-load.service" conditional='HAVE_KMOD'
+          xmlns:xi="http://www.w3.org/2001/XInclude">
 
   <refentryinfo>
     <title>systemd-modules-load.service</title>
diff --git a/man/systemd-network-generator.service.xml b/man/systemd-network-generator.service.xml
index 13f0936469..d1584b89cc 100644
--- a/man/systemd-network-generator.service.xml
+++ b/man/systemd-network-generator.service.xml
@@ -3,7 +3,7 @@
   "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
 <!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
 
-<refentry id="systemd-network-generator.service">
+<refentry id="systemd-network-generator.service" xmlns:xi="http://www.w3.org/2001/XInclude">
 
   <refentryinfo>
     <title>systemd-network-generator.service</title>
diff --git a/man/systemd-quotacheck.service.xml b/man/systemd-quotacheck.service.xml
index 4e2a5a43eb..8d80f272bf 100644
--- a/man/systemd-quotacheck.service.xml
+++ b/man/systemd-quotacheck.service.xml
@@ -3,7 +3,8 @@
 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
   "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
 <!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
-<refentry id="systemd-quotacheck.service" conditional='ENABLE_QUOTACHECK'>
+<refentry id="systemd-quotacheck.service" conditional='ENABLE_QUOTACHECK'
+          xmlns:xi="http://www.w3.org/2001/XInclude">
 
   <refentryinfo>
     <title>systemd-quotacheck.service</title>
diff --git a/man/systemd-random-seed.service.xml b/man/systemd-random-seed.service.xml
index 59bb66e935..4dda01487f 100644
--- a/man/systemd-random-seed.service.xml
+++ b/man/systemd-random-seed.service.xml
@@ -3,7 +3,8 @@
 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
   "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
 <!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
-<refentry id="systemd-random-seed.service" conditional='ENABLE_RANDOMSEED'>
+<refentry id="systemd-random-seed.service" conditional='ENABLE_RANDOMSEED'
+          xmlns:xi="http://www.w3.org/2001/XInclude">
 
   <refentryinfo>
     <title>systemd-random-seed.service</title>
diff --git a/man/systemd-resolved.service.xml b/man/systemd-resolved.service.xml
index 5a87f04832..4fba1964a0 100644
--- a/man/systemd-resolved.service.xml
+++ b/man/systemd-resolved.service.xml
@@ -3,7 +3,8 @@
   "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
 <!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
 
-<refentry id="systemd-resolved.service" conditional='ENABLE_RESOLVE'>
+<refentry id="systemd-resolved.service" conditional='ENABLE_RESOLVE'
+          xmlns:xi="http://www.w3.org/2001/XInclude">
 
   <refentryinfo>
     <title>systemd-resolved.service</title>
diff --git a/man/systemd-rfkill.service.xml b/man/systemd-rfkill.service.xml
index d89eb91d43..7aa965284d 100644
--- a/man/systemd-rfkill.service.xml
+++ b/man/systemd-rfkill.service.xml
@@ -3,7 +3,8 @@
 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
   "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
 <!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
-<refentry id="systemd-rfkill.service" conditional='ENABLE_RFKILL'>
+<refentry id="systemd-rfkill.service" conditional='ENABLE_RFKILL'
+          xmlns:xi="http://www.w3.org/2001/XInclude">
 
   <refentryinfo>
     <title>systemd-rfkill.service</title>
diff --git a/man/systemd-time-wait-sync.service.xml b/man/systemd-time-wait-sync.service.xml
index cd26ae4f0b..887a9e306b 100644
--- a/man/systemd-time-wait-sync.service.xml
+++ b/man/systemd-time-wait-sync.service.xml
@@ -3,7 +3,8 @@
   "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
 <!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
 
-<refentry id="systemd-time-wait-sync.service" conditional='ENABLE_TIMESYNCD'>
+<refentry id="systemd-time-wait-sync.service" conditional='ENABLE_TIMESYNCD'
+          xmlns:xi="http://www.w3.org/2001/XInclude">
 
   <refentryinfo>
     <title>systemd-time-wait-sync.service</title>
diff --git a/man/systemd-timesyncd.service.xml b/man/systemd-timesyncd.service.xml
index 45fb6b716f..ac6aae6a33 100644
--- a/man/systemd-timesyncd.service.xml
+++ b/man/systemd-timesyncd.service.xml
@@ -3,7 +3,8 @@
   "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
 <!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
 
-<refentry id="systemd-timesyncd.service" conditional='ENABLE_TIMESYNCD'>
+<refentry id="systemd-timesyncd.service" conditional='ENABLE_TIMESYNCD'
+          xmlns:xi="http://www.w3.org/2001/XInclude">
 
   <refentryinfo>
     <title>systemd-timesyncd.service</title>
diff --git a/man/systemd-vconsole-setup.service.xml b/man/systemd-vconsole-setup.service.xml
index d156c482db..72196d2d90 100644
--- a/man/systemd-vconsole-setup.service.xml
+++ b/man/systemd-vconsole-setup.service.xml
@@ -3,7 +3,8 @@
 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
   "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
 <!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
-<refentry id="systemd-vconsole-setup.service" conditional='ENABLE_VCONSOLE'>
+<refentry id="systemd-vconsole-setup.service" conditional='ENABLE_VCONSOLE'
+          xmlns:xi="http://www.w3.org/2001/XInclude">
 
   <refentryinfo>
     <title>systemd-vconsole-setup.service</title>
diff --git a/man/systemd-veritysetup-generator.xml b/man/systemd-veritysetup-generator.xml
index cbf754985d..6e6f52839b 100644
--- a/man/systemd-veritysetup-generator.xml
+++ b/man/systemd-veritysetup-generator.xml
@@ -3,7 +3,8 @@
 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
   "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
 <!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
-<refentry id="systemd-veritysetup-generator" conditional='HAVE_LIBCRYPTSETUP'>
+<refentry id="systemd-veritysetup-generator" conditional='HAVE_LIBCRYPTSETUP'
+          xmlns:xi="http://www.w3.org/2001/XInclude">
 
   <refentryinfo>
     <title>systemd-veritysetup-generator</title>
diff --git a/man/systemd-veritysetup@.service.xml b/man/systemd-veritysetup@.service.xml
index 423db91223..ed91bd288f 100644
--- a/man/systemd-veritysetup@.service.xml
+++ b/man/systemd-veritysetup@.service.xml
@@ -3,7 +3,8 @@
 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
   "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
 <!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
-<refentry id="systemd-veritysetup@.service" conditional='HAVE_LIBCRYPTSETUP'>
+<refentry id="systemd-veritysetup@.service" conditional='HAVE_LIBCRYPTSETUP'
+          xmlns:xi="http://www.w3.org/2001/XInclude">
 
   <refentryinfo>
     <title>systemd-veritysetup@.service</title>
diff --git a/man/systemd.generator.xml b/man/systemd.generator.xml
index 1455b8cdda..3af240b6d8 100644
--- a/man/systemd.generator.xml
+++ b/man/systemd.generator.xml
@@ -6,7 +6,7 @@
 ]>
 <!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
 
-<refentry id="systemd.generator">
+<refentry id="systemd.generator" xmlns:xi="http://www.w3.org/2001/XInclude">
   <refentryinfo>
     <title>systemd.generator</title>
     <productname>systemd</productname>
diff --git a/man/systemd.journal-fields.xml b/man/systemd.journal-fields.xml
index 2c6fd2079d..9971c7f64b 100644
--- a/man/systemd.journal-fields.xml
+++ b/man/systemd.journal-fields.xml
@@ -3,7 +3,7 @@
   "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
 <!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
 
-<refentry id="systemd.journal-fields">
+<refentry id="systemd.journal-fields" xmlns:xi="http://www.w3.org/2001/XInclude">
 
   <refentryinfo>
     <title>systemd.journal-fields</title>
diff --git a/man/systemd.kill.xml b/man/systemd.kill.xml
index 91de22f39e..862e228427 100644
--- a/man/systemd.kill.xml
+++ b/man/systemd.kill.xml
@@ -3,7 +3,7 @@
   "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
 <!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
 
-<refentry id="systemd.kill">
+<refentry id="systemd.kill" xmlns:xi="http://www.w3.org/2001/XInclude">
   <refentryinfo>
     <title>systemd.kill</title>
     <productname>systemd</productname>
diff --git a/man/systemd.net-naming-scheme.xml b/man/systemd.net-naming-scheme.xml
index 2be0295bf1..c8df10b128 100644
--- a/man/systemd.net-naming-scheme.xml
+++ b/man/systemd.net-naming-scheme.xml
@@ -3,7 +3,7 @@
   "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
 <!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
 
-<refentry id="systemd.net-naming-scheme">
+<refentry id="systemd.net-naming-scheme" xmlns:xi="http://www.w3.org/2001/XInclude">
   <refentryinfo>
     <title>systemd.net-naming-scheme</title>
     <productname>systemd</productname>
diff --git a/man/systemd.nspawn.xml b/man/systemd.nspawn.xml
index f60d1d83a0..0540b85dc6 100644
--- a/man/systemd.nspawn.xml
+++ b/man/systemd.nspawn.xml
@@ -6,7 +6,7 @@
 ]>
 <!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
 
-<refentry id="systemd.nspawn">
+<refentry id="systemd.nspawn" xmlns:xi="http://www.w3.org/2001/XInclude">
 
   <refentryinfo>
     <title>systemd.nspawn</title>
diff --git a/man/systemd.service.xml b/man/systemd.service.xml
index e37de65a77..e9c431bd68 100644
--- a/man/systemd.service.xml
+++ b/man/systemd.service.xml
@@ -3,7 +3,7 @@
   "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
 <!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
 
-<refentry id="systemd.service">
+<refentry id="systemd.service" xmlns:xi="http://www.w3.org/2001/XInclude">
   <refentryinfo>
     <title>systemd.service</title>
     <productname>systemd</productname>
diff --git a/man/systemd.special.xml b/man/systemd.special.xml
index 7d2c3f404b..4b5e54b27d 100644
--- a/man/systemd.special.xml
+++ b/man/systemd.special.xml
@@ -3,7 +3,7 @@
   "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
 <!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
 
-<refentry id="systemd.special">
+<refentry id="systemd.special" xmlns:xi="http://www.w3.org/2001/XInclude">
 
   <refentryinfo>
     <title>systemd.special</title>
diff --git a/man/systemd.system-credentials.xml b/man/systemd.system-credentials.xml
index 0e64b45df0..b190ba5109 100644
--- a/man/systemd.system-credentials.xml
+++ b/man/systemd.system-credentials.xml
@@ -3,7 +3,7 @@
   "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
 <!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
 
-<refentry id="systemd.system-credentials">
+<refentry id="systemd.system-credentials" xmlns:xi="http://www.w3.org/2001/XInclude">
 
   <refentryinfo>
     <title>systemd.system-credentials</title>
diff --git a/man/udev.xml b/man/udev.xml
index 5533c68a0d..3bfa355b6f 100644
--- a/man/udev.xml
+++ b/man/udev.xml
@@ -7,7 +7,7 @@
   Copyright © 2014 Jason St. John
 -->
 
-<refentry id="udev">
+<refentry id="udev" xmlns:xi="http://www.w3.org/2001/XInclude">
   <refentryinfo>
     <title>udev</title>
     <productname>systemd</productname>
diff --git a/man/vconsole.conf.xml b/man/vconsole.conf.xml
index eb1f20d224..07959d837a 100644
--- a/man/vconsole.conf.xml
+++ b/man/vconsole.conf.xml
@@ -6,7 +6,8 @@
 ]>
 <!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
 
-<refentry id="vconsole.conf" conditional='ENABLE_VCONSOLE'>
+<refentry id="vconsole.conf" conditional='ENABLE_VCONSOLE'
+          xmlns:xi="http://www.w3.org/2001/XInclude">
   <refentryinfo>
     <title>vconsole.conf</title>
     <productname>systemd</productname>