make install do not support DESTDIR variable

diff --git a/Makefile.in b/Makefile.in
index 6b967cf..d97319d 100644
--- a/Makefile.in
+++ b/Makefile.in
@@ -33,6 +33,7 @@ INSTALL_DOC = $(INSTALL) -m 644
 INSTALL_BIN = $(INSTALL) -m 755
 INSTALL_DIR = $(INSTALL) -m 755 -d
 
+DESTDIR =
 prefix		= @prefix@
 exec_prefix	= @exec_prefix@
 sbindir		= @sbindir@
@@ -109,13 +110,13 @@ all:	$(BINS)
 dbgs: $(DBGS)
 
 install: $(BINS)
-	$(INSTALL_DIR) $(sbindir)
+	$(INSTALL_DIR) $(DESTDIR)$(sbindir)
 	for file in $(BINS); do \
-	$(INSTALL_BIN) "$$file" $(sbindir) ; \
+	$(INSTALL_BIN) "$$file" $(DESTDIR)$(sbindir) ; \
 	done	
-	$(INSTALL_DIR) $(mandir) $(mandir)/man1
+	$(INSTALL_DIR) $(mandir) $(DESTDIR)$(mandir)/man1
 	for file in mtx.1 tapeinfo.1 scsitape.1 scsieject.1 loaderinfo.1 ; do \
-	$(INSTALL_DOC) "$$file"  $(mandir)/man1 ; \
+	$(INSTALL_DOC)  $(srcdir)/"$$file"  $(DESTDIR)$(mandir)/man1 ; \
 	done
 
 clean: