diff --git a/devel/sdts++/Makefile b/devel/sdts++/Makefile
index b0191ce4b231..918b94fb27a4 100644
--- a/devel/sdts++/Makefile
+++ b/devel/sdts++/Makefile
@@ -1,37 +1,40 @@
 PORTNAME=	sdts++
 PORTVERSION=	1.5.1
 PORTREVISION=	21
 CATEGORIES=	devel
 MASTER_SITES=	http://thor-f5.er.usgs.gov/sdts/sdtsxx/ \
 		http://lychnobite.org/sdts/
 
 MAINTAINER=	ports@FreeBSD.org
 COMMENT=	C++ library for SDTS related development
 WWW=		https://mcmcweb.er.usgs.gov/sdts/sdtsxx/
 
+DEPRECATED=	Last upstream release was in 2003 and both MASTER_SITES and WWW are unreachable
+EXPIRATION_DATE=	2023-11-22
+
 LIB_DEPENDS=	libboost_thread.so:devel/boost-libs
 
 USES=		autoreconf bison dos2unix gmake libtool makeinfo
 DOS2UNIX_GLOB=	*.cpp
 USE_CXXSTD=	c++14
 USE_LDCONFIG=	yes
 
 GNU_CONFIGURE=	yes
 CONFIGURE_ARGS=	--with-boost=${LOCALBASE}/include
 
 INSTALL_TARGET=	install-strip
 
 INFO=		sdts++
 
 .include <bsd.port.options.mk>
 
 .if ${OPSYS} == FreeBSD && ( ${OSVERSION} >= 1400091 || ( ${OSVERSION} >= 1302507 && ${OSVERSION} < 1400000 ))
 CPPFLAGS+=  -Dregister=
 .endif
 
 post-patch:
 .for f in AUTHORS ChangeLog NEWS README
 	@${TOUCH} ${WRKSRC}/sysutils/${f}
 .endfor
 
 .include <bsd.port.mk>