diff --git a/src/libudev/libudev-device-internal.h b/src/libudev/libudev-device-internal.h
index b0c4b188bc..c872973091 100644
--- a/src/libudev/libudev-device-internal.h
+++ b/src/libudev/libudev-device-internal.h
@@ -2,7 +2,8 @@
 #pragma once
 
 #include "libudev.h"
-#include "sd-device.h"
+
+#include "forward.h"
 
 struct udev_device;
 
diff --git a/src/libudev/libudev-device.c b/src/libudev/libudev-device.c
index 4ad1489307..d7ccadae66 100644
--- a/src/libudev/libudev-device.c
+++ b/src/libudev/libudev-device.c
@@ -1,21 +1,5 @@
 /* SPDX-License-Identifier: LGPL-2.1-or-later */
 
-#include <ctype.h>
-#include <dirent.h>
-#include <errno.h>
-#include <fcntl.h>
-#include <linux/sockios.h>
-#include <net/if.h>
-#include <stdbool.h>
-#include <stddef.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-#include <sys/ioctl.h>
-#include <sys/socket.h>
-#include <sys/stat.h>
-#include <unistd.h>
-
 #include "libudev.h"
 #include "sd-device.h"
 
@@ -25,8 +9,6 @@
 #include "errno-util.h"
 #include "libudev-device-internal.h"
 #include "libudev-list-internal.h"
-#include "parse-util.h"
-#include "time-util.h"
 
 /**
  * SECTION:libudev-device
diff --git a/src/libudev/libudev-enumerate.c b/src/libudev/libudev-enumerate.c
index 6afcc68256..d4d670106b 100644
--- a/src/libudev/libudev-enumerate.c
+++ b/src/libudev/libudev-enumerate.c
@@ -1,21 +1,10 @@
 /* SPDX-License-Identifier: LGPL-2.1-or-later */
 
-#include <dirent.h>
-#include <errno.h>
-#include <fnmatch.h>
-#include <stdbool.h>
-#include <stddef.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-#include <sys/stat.h>
-
 #include "libudev.h"
 #include "sd-device.h"
 
 #include "alloc-util.h"
 #include "device-enumerator-private.h"
-#include "device-util.h"
 #include "errno-util.h"
 #include "libudev-device-internal.h"
 #include "libudev-list-internal.h"
diff --git a/src/libudev/libudev-hwdb.c b/src/libudev/libudev-hwdb.c
index edc1c664a8..5087e04ee8 100644
--- a/src/libudev/libudev-hwdb.c
+++ b/src/libudev/libudev-hwdb.c
@@ -1,15 +1,10 @@
 /* SPDX-License-Identifier: LGPL-2.1-or-later */
 
-#include <errno.h>
-
 #include "sd-hwdb.h"
 
 #include "alloc-util.h"
-#include "assert-util.h"
 #include "errno-util.h"
-#include "hwdb-util.h"
 #include "libudev-list-internal.h"
-#include "log.h"
 
 /**
  * SECTION:libudev-hwdb
diff --git a/src/libudev/libudev-list-internal.h b/src/libudev/libudev-list-internal.h
index dd4fcbc771..efe394d1fd 100644
--- a/src/libudev/libudev-list-internal.h
+++ b/src/libudev/libudev-list-internal.h
@@ -3,7 +3,7 @@
 
 #include "libudev.h"
 
-#include "memory-util.h"
+#include "forward.h"
 
 struct udev_list;
 
diff --git a/src/libudev/libudev-list.c b/src/libudev/libudev-list.c
index 4f9e58fe1b..4c4de297b9 100644
--- a/src/libudev/libudev-list.c
+++ b/src/libudev/libudev-list.c
@@ -4,6 +4,7 @@
 #include "hashmap.h"
 #include "libudev-list-internal.h"
 #include "list.h"
+#include "string-util.h"
 
 /**
  * SECTION:libudev-list
diff --git a/src/libudev/libudev-monitor.c b/src/libudev/libudev-monitor.c
index 0682ab9cd6..c82f9c0151 100644
--- a/src/libudev/libudev-monitor.c
+++ b/src/libudev/libudev-monitor.c
@@ -1,14 +1,13 @@
 /* SPDX-License-Identifier: LGPL-2.1-or-later */
 
-#include <errno.h>
 #include <poll.h>
 
 #include "libudev.h"
+#include "sd-device.h"
 
 #include "alloc-util.h"
 #include "device-monitor-private.h"
-#include "device-private.h"
-#include "device-util.h"
+#include "errno-util.h"
 #include "io-util.h"
 #include "libudev-device-internal.h"
 #include "string-util.h"
diff --git a/src/libudev/libudev-queue.c b/src/libudev/libudev-queue.c
index 852bd370ed..a6064e5b66 100644
--- a/src/libudev/libudev-queue.c
+++ b/src/libudev/libudev-queue.c
@@ -3,7 +3,6 @@
   Copyright © 2009 Alan Jenkins <alan-jenkins@tuffmail.co.uk>
 ***/
 
-#include <errno.h>
 #include <sys/inotify.h>
 #include <unistd.h>
 
diff --git a/src/libudev/libudev-util.c b/src/libudev/libudev-util.c
index 8c51877662..5ee9ebd03e 100644
--- a/src/libudev/libudev-util.c
+++ b/src/libudev/libudev-util.c
@@ -1,7 +1,9 @@
 /* SPDX-License-Identifier: LGPL-2.1-or-later */
 
+#include "libudev.h"
+
+#include "forward.h"
 #include "device-nodes.h"
-#include "libudev-util.h"
 
 /**
  * SECTION:libudev-util
diff --git a/src/libudev/libudev-util.h b/src/libudev/libudev-util.h
index a02021845d..eb899f9f1d 100644
--- a/src/libudev/libudev-util.h
+++ b/src/libudev/libudev-util.h
@@ -3,8 +3,7 @@
 
 #include "libudev.h"
 
-#include "macro.h"
-#include "memory-util.h"
+#include "forward.h"
 
 /* Cleanup functions */
 DEFINE_TRIVIAL_CLEANUP_FUNC(struct udev*, udev_unref);
diff --git a/src/libudev/libudev.c b/src/libudev/libudev.c
index ae3260633a..659aa2b743 100644
--- a/src/libudev/libudev.c
+++ b/src/libudev/libudev.c
@@ -1,18 +1,12 @@
 /* SPDX-License-Identifier: LGPL-2.1-or-later */
 
-#include <ctype.h>
-#include <stdarg.h>
-#include <stddef.h>
 #include <stdio.h>
-#include <stdlib.h>
 
 #include "libudev.h"
 
 #include "alloc-util.h"
 #include "errno-util.h"
-#include "fd-util.h"
 #include "log.h"
-#include "string-util.h"
 
 /**
  * SECTION:libudev
diff --git a/src/libudev/test-libudev.c b/src/libudev/test-libudev.c
index 99934c6f03..63c2403124 100644
--- a/src/libudev/test-libudev.c
+++ b/src/libudev/test-libudev.c
@@ -1,18 +1,15 @@
 /* SPDX-License-Identifier: LGPL-2.1-or-later */
 
-#include <errno.h>
 #include <getopt.h>
 #include <sys/epoll.h>
 #include <unistd.h>
 
-#include "alloc-util.h"
 #include "devnum-util.h"
 #include "fd-util.h"
 #include "libudev-list-internal.h"
-#include "libudev-util.h"
 #include "log.h"
 #include "main-func.h"
-#include "stdio-util.h"
+#include "libudev-util.h"
 #include "string-util.h"
 #include "tests.h"
 #include "version.h"
diff --git a/src/libudev/test-udev-device-thread.c b/src/libudev/test-udev-device-thread.c
index c12480f89c..78fd3b24bf 100644
--- a/src/libudev/test-udev-device-thread.c
+++ b/src/libudev/test-udev-device-thread.c
@@ -1,9 +1,7 @@
 /* SPDX-License-Identifier: LGPL-2.1-or-later */
 
-#include <errno.h>
 #include <pthread.h>
 #include <stdio.h>
-#include <stdlib.h>
 
 #include "libudev.h"
 
@@ -11,7 +9,7 @@
 
 #define handle_error_errno(error, msg)                          \
         ({                                                      \
-                errno = abs(error);                             \
+                errno = ABS(error);                             \
                 perror(msg);                                    \
                 EXIT_FAILURE;                                   \
         })