--- Makefile.orig	2014-01-14 00:24:40.000000000 +0100
+++ Makefile	2014-01-14 00:25:34.000000000 +0100
@@ -1,3 +1,4 @@
+DESTDIR?=
 PREFIX?=/usr/local
 MANDIR?=$(PREFIX)/share/man
 MAN1DIR=$(MANDIR)/man1
@@ -67,11 +68,11 @@
 	$(RM) $(CFLOWMAN).gz $(CMAN).gz $(ASMMAN).gz
 
 install: mkdirs build
-	$(INSTALL) -d $(PREFIX)/bin
-	$(INSTALL) -c -m 0755 $(CFLOW) $(PREFIX)/bin/$(CFLOW)
-	$(INSTALL) -c -m 0755 $(ASMPROG) $(PREFIX)/bin/$(ASMPROG)
-	$(INSTALL) -c -m 0755 $(CPROG) $(PREFIX)/bin/$(CPROG)
-	$(INSTALL) -d $(MAN1DIR)
-	$(INSTALL) -c -m 0644 $(CFLOWMAN).gz $(MAN1DIR)/$(CFLOWMAN).gz
-	$(INSTALL) -c -m 0644 $(ASMMAN).gz $(MAN1DIR)/$(ASMMAN).gz
-	$(INSTALL) -c -m 0644 $(CMAN).gz $(MAN1DIR)/$(CMAN).gz
+	$(INSTALL) -d $(DESTDIR)$(PREFIX)/bin
+	$(INSTALL) -c -m 0755 $(CFLOW) $(DESTDIR)$(PREFIX)/bin/$(CFLOW)
+	$(INSTALL) -c -m 0755 $(ASMPROG) $(DESTDIR)$(PREFIX)/bin/$(ASMPROG)
+	$(INSTALL) -c -m 0755 $(CPROG) $(DESTDIR)$(PREFIX)/bin/$(CPROG)
+	$(INSTALL) -d $(DESTDIR)$(MAN1DIR)
+	$(INSTALL) -c -m 0644 $(CFLOWMAN).gz $(DESTDIR)$(MAN1DIR)/$(CFLOWMAN).gz
+	$(INSTALL) -c -m 0644 $(ASMMAN).gz $(DESTDIR)$(MAN1DIR)/$(ASMMAN).gz
+	$(INSTALL) -c -m 0644 $(CMAN).gz $(DESTDIR)$(MAN1DIR)/$(CMAN).gz