--- a/Makefile	2017-09-24 22:48:19.322116085 +0200
+++ b/Makefile	2017-09-24 22:50:07.655725022 +0200
@@ -19,7 +19,7 @@
 CFLAGS += -O2 -Wall
 
 INSTALL = install
-DESTDIR = /usr/local/bin
+DESTDIR ?= /usr/local/bin
 
 OBJECTS = $(NAME).o sha512.o
 
@@ -38,8 +38,8 @@
 	@python -m pytest test.py -s -q
 
 install: $(NAME)
-	$(INSTALL) -d $(DEST_DIR)
-	$(INSTALL) $(NAME) $(DEST_DIR)
+	$(INSTALL) -d $(DESTDIR)
+	$(INSTALL) $(NAME) $(DESTDIR)
 
 clean:
 	rm -f $(OBJECTS)