diff -ruN /usr/ports/cad/openvsp/Makefile cad/openvsp/Makefile
--- /usr/ports/cad/openvsp/Makefile	2015-08-30 19:41:23.000000000 +0200
+++ cad/openvsp/Makefile	2016-02-16 18:46:52.471715000 +0100
@@ -29,7 +29,7 @@
 GH_ACCOUNT=	${GH_PROJECT}
 
 CMAKE_SOURCE_PATH=	${WRKSRC}/src
-USES=		cmake:outsource dos2unix jpeg
+USES=		compiler:gcc-c++11-lib cmake:outsource dos2unix jpeg
 USE_XORG=	ice sm x11 xau xcb xdamage xdmcp xext xfixes xft \
 		xinerama xrender xxf86vm
 USE_GL=		glu