--- Makefile.orig	2007-01-15 02:57:19.000000000 +0800
+++ Makefile	2014-08-27 10:57:44.239551223 +0800
@@ -19,15 +19,15 @@ $(LIBNAME): $(OBJS)
 	$(CC) $(CFLAGS) $(LIB_OPTION) -o $(LIBNAME) $(OBJS) $(LIBS)
 
 install: $(LIBNAME)
-	mkdir -p $(LUA_LIBDIR)
+	mkdir -p $(DESTDIR)$(LUA_LIBDIR)
 	strip $(LIBNAME)
-	cp $(LIBNAME) $(LUA_LIBDIR)
-	(cd $(LUA_LIBDIR) ; rm -f $T$(LIB_EXT) ; ln -fs $(LIBNAME) $T$(LIB_EXT))
+	cp $(LIBNAME) $(DESTDIR)$(LUA_LIBDIR)
+	(cd $(DESTDIR)$(LUA_LIBDIR) ; rm -f $T$(LIB_EXT) ; ln -fs $(LIBNAME) $T$(LIB_EXT))
 
 install_spamfilter:
-	mkdir -p $(SPAMFILTER_DIR)
-	cp spamfilter/* $(SPAMFILTER_DIR)
-	chmod 755 $(SPAMFILTER_DIR)/*.lua
+	mkdir -p $(DESTDIR)$(SPAMFILTER_DIR)
+	cp spamfilter/* $(DESTDIR)$(SPAMFILTER_DIR)
+	chmod 755 $(DESTDIR)$(SPAMFILTER_DIR)/*.lua
 
 clean:
 	rm -f $L $(LIBNAME) $(OBJS) *.so *~ spamfilter/*~