diff --git a/Makefile b/Makefile
index e0b8676..3fc4be5 100644
--- a/Makefile
+++ b/Makefile
@@ -1,24 +1,25 @@
 # Makefile for postplug
-# Copyright (C) 2004-2015 by Silvan Calarco <silvan.calarco@qilinux.it>
+# Copyright (C) 2004-2024 by Silvan Calarco <silvan.calarco@qilinux.it>
 # Copyright (C) 2004-2007 by Davide Madrisan <davide.madrisan@gmail.com>
 
 include VERSION
 
 PACKAGE = postplug
 
-prefix = /usr
-exec_prefix = $(prefix)
-sysconfdir = /etc
+prefix := /usr
+exec_prefix := $(prefix)
+sysconfdir := /etc
 bindir = $(exec_prefix)/bin
 libdir := $(prefix)/lib
-sbindir = $(exec_prefix)/sbin
-sbin = /sbin
+sbindir := $(bindir)
+sbin := $(bindir)
 mandir = $(prefix)/share/man
 datadir = $(prefix)/share
-initrddir = $(sysconfdir)/rc.d/init.d
 logrotatedir = $(sysconfdir)/logrotate.d/
 sysconfigdir= $(sysconfdir)/sysconfig
-systemdunitdir = /usr/lib/systemd/system
+systemdunitdir := $(prefix)/lib/systemd/system
+udevdir := $(prefix)/lib/udev
+udevrulesdir := $(udevdir)/rules.d
 localesdir = $(datadir)/locale
 
 srcdir = .
@@ -94,9 +95,9 @@ install-plugins: $(pck_plugins)
 
 install-udev-files:
 	@echo "installing udev files..."
-	@$(INSTALL_DIR) $(DESTDIR)/lib/udev/rules.d
-	$(INSTALL_SCRIPT) udev/android_usb $(DESTDIR)/lib/udev/android_usb
-	$(INSTALL_DATA) udev/76-android_usb.rules $(DESTDIR)/lib/udev/rules.d/76-android_usb.rules
+	@$(INSTALL_DIR) $(DESTDIR)$(udevrulesdir)
+	$(INSTALL_SCRIPT) udev/android_usb $(DESTDIR)$(udevdir)/android_usb
+	$(INSTALL_DATA) udev/76-android_usb.rules $(DESTDIR)$(udevrulesdir)/76-android_usb.rules
 
 install-sysconfig: $(pck_sysconfig)
 	@$(INSTALL_DIR) $(DESTDIR)$(sysconfigdir)