diff --git a/.gitignore b/.gitignore
index 651dd4e..3392289 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,2 +1,3 @@
+/config/active.mk
 /polytreewm
 /src/*.o
diff --git a/Makefile b/Makefile
index 8a372c1..8ab498c 100644
--- a/Makefile
+++ b/Makefile
@@ -1,7 +1,16 @@
 # PolytreeWM - tiling window manager
 # See LICENSE file for copyright and license details.
 
-include config.mk
+include config/active.mk
+
+VERSION = 6.2
+
+INCS = -I$(X11INC) -I$(FREETYPEINC)
+LIBS = -L$(X11LIB) -lX11 $(XINERAMALIBS) $(FREETYPELIBS) -lX11-xcb -lxcb -lxcb-res $(KVMLIB)
+
+CPPFLAGS = -DVERSION=\"$(VERSION)\" -D_DEFAULT_SOURCE -D_BSD_SOURCE -D_POSIX_C_SOURCE=200809L -DXINERAMA
+CFLAGS   = -std=c99 -pedantic -Wall -Wno-deprecated-declarations -Os $(INCS) $(CPPFLAGS)
+LDFLAGS  = $(LIBS)
 
 SRC = \
 	src/atoms.c \
@@ -56,6 +65,9 @@ ${OBJ}: config.mk ${HDR}
 clean:
 	rm -f polytreewm ${OBJ}
 
+distclean: clean
+	rm -f config/active.mk
+
 install: all
 	mkdir -p ${DESTDIR}${PREFIX}/bin
 	cp -f polytreewm ${DESTDIR}${PREFIX}/bin
@@ -70,4 +82,4 @@ uninstall:
 		${DESTDIR}${PREFIX}/bin/polytreewm \
 		${DESTDIR}${MANPREFIX}/man1/polytreewm.1
 
-.PHONY: all options clean install uninstall
+.PHONY: all options clean distclean install uninstall
diff --git a/config.mk b/config.mk
deleted file mode 100644
index b605bae..0000000
--- a/config.mk
+++ /dev/null
@@ -1,44 +0,0 @@
-# PolytreeWM version
-VERSION = 6.2
-
-# Customize below to fit your system
-
-# paths
-PREFIX = /usr/local
-MANPREFIX = ${PREFIX}/share/man
-
-X11INC = /usr/X11R6/include
-X11LIB = /usr/X11R6/lib
-# FreeBSD (uncomment)
-#X11INC = /usr/local/include
-#X11LIB = /usr/local/lib
-
-# Xinerama, comment if you don't want it
-XINERAMALIBS  = -lXinerama
-XINERAMAFLAGS = -DXINERAMA
-
-# freetype
-FREETYPELIBS = -lfontconfig -lXft
-FREETYPEINC = /usr/include/freetype2
-# FreeBSD (uncomment)
-#FREETYPEINC = /usr/local/include/freetype2
-# OpenBSD (uncomment)
-#FREETYPEINC = ${X11INC}/freetype2
-#KVMLIB = -lkvm
-
-# includes and libs
-INCS = -I${X11INC} -I${FREETYPEINC}
-LIBS = -L${X11LIB} -lX11 ${XINERAMALIBS} ${FREETYPELIBS} -lX11-xcb -lxcb -lxcb-res ${KVMLIB}
-
-# flags
-CPPFLAGS = -D_DEFAULT_SOURCE -D_BSD_SOURCE -D_POSIX_C_SOURCE=200809L -DVERSION=\"${VERSION}\" ${XINERAMAFLAGS}
-#CFLAGS   = -g -std=c99 -pedantic -Wall -O0 ${INCS} ${CPPFLAGS}
-CFLAGS   = -std=c99 -pedantic -Wall -Wno-deprecated-declarations -Os ${INCS} ${CPPFLAGS}
-LDFLAGS  = ${LIBS}
-
-# Solaris
-#CFLAGS = -fast ${INCS} -DVERSION=\"${VERSION}\"
-#LDFLAGS = ${LIBS}
-
-# compiler and linker
-CC = cc
diff --git a/config/default.mk b/config/default.mk
new file mode 100644
index 0000000..a60edf3
--- /dev/null
+++ b/config/default.mk
@@ -0,0 +1,24 @@
+##########################
+# Compiler, linker, etc. #
+##########################
+
+CC = cc
+
+#########
+# Paths #
+#########
+
+PREFIX = /usr/local
+MANPREFIX = $(PREFIX)/share/man
+
+################
+# Dependencies #
+################
+
+X11INC = /usr/X11R6/include
+X11LIB = /usr/X11R6/lib
+
+XINERAMALIBS  = -lXinerama
+
+FREETYPELIBS = -lfontconfig -lXft
+FREETYPEINC = /usr/include/freetype2
diff --git a/config/freebsd.mk b/config/freebsd.mk
new file mode 100644
index 0000000..ca7b902
--- /dev/null
+++ b/config/freebsd.mk
@@ -0,0 +1,6 @@
+include default.mk
+
+X11INC = /usr/local/include
+X11LIB = /usr/local/lib
+
+FREETYPEINC = /usr/include/freetype2
diff --git a/config/openbsd.mk b/config/openbsd.mk
new file mode 100644
index 0000000..4e6ee3e
--- /dev/null
+++ b/config/openbsd.mk
@@ -0,0 +1,5 @@
+include default.mk
+
+FREETYPEINC = $(X11INC)/freetype2
+
+KVMLIB = -lkvm
diff --git a/configure b/configure
new file mode 100755
index 0000000..5596dd3
--- /dev/null
+++ b/configure
@@ -0,0 +1,5 @@
+#!/bin/sh
+
+set -e
+
+ln -sf default.mk config/active.mk