--- Makefile.orig	2014-06-27 00:40:28.370101738 +0800
+++ Makefile	2014-06-27 00:40:53.285115312 +0800
@@ -8,8 +8,8 @@ $(NAME): $(NAME).c
 	$(CC) $(CFLAGS) -o $@ $? -lm
 
 install: $(NAME)
-	$(INSTALL) -s $(NAME) $(PREFIX)/bin
-	gzip -c $(NAME).1 >$(PREFIX)/man/man1/$(NAME).1.gz
+	$(INSTALL) -s $(NAME) $(DESTDIR)$(PREFIX)/bin
+	gzip -c $(NAME).1 > $(DESTDIR)$(PREFIX)/man/man1/$(NAME).1.gz
 
 clean:
 	rm -f $(NAME) $(NAME).o