diff -ruN -x CVS pkgsrc-2017Q2/x11/tk/options.mk pkgsrc/x11/tk/options.mk
--- pkgsrc-2017Q2/x11/tk/options.mk	2016-09-03 13:58:02.000000000 +0200
+++ pkgsrc/x11/tk/options.mk	2017-08-07 11:48:32.780105120 +0200
@@ -1,7 +1,7 @@
 # $NetBSD: options.mk,v 1.5 2016/09/03 11:58:02 adam Exp $
 
 PKG_OPTIONS_VAR=	PKG_OPTIONS.tk
-PKG_SUPPORTED_OPTIONS=	threads debug xft2
+PKG_SUPPORTED_OPTIONS=	threads debug xft2 xscreensaver
 PKG_SUGGESTED_OPTIONS=	threads
 
 .include "../../mk/bsd.prefs.mk"
@@ -44,3 +44,11 @@
 .else
 CONFIGURE_ARGS+=	--disable-xft
 .endif
+
+.if !empty(PKG_OPTIONS:Mxscreensaver)
+CONFIGURE_ARGS+=	--enable-xss
+USE_TOOLS+=		pkg-config
+.include "../../x11/libXScrnSaver/buildlink3.mk"
+.else
+CONFIGURE_ARGS+=	--disable-xss
+.endif