diff --git a/science/qwalk/Makefile b/science/qwalk/Makefile
index 570c53ed651f..80dbc8d5497d 100644
--- a/science/qwalk/Makefile
+++ b/science/qwalk/Makefile
@@ -1,26 +1,28 @@
 PORTNAME=	qwalk
 DISTVERSIONPREFIX=	v
 DISTVERSION=	1.0.1-300
 PORTREVISION=	6
 DISTVERSIONSUFFIX=	-g1b7e381
 CATEGORIES=	science
 
 MAINTAINER=	yuri@FreeBSD.org
 COMMENT=	Quantum Monte Carlo package for quantum chemistry computations
 WWW=		https://qwalk.github.io/mainline/
 
 LICENSE=	GPLv2
 LICENSE_FILE=	${WRKSRC}/../COPYING
 
 PORTSCOUT=	limit:^.*[1-9]\. # prevent words like 'broken'
 
 USES=		compiler:c++11-lang fortran gmake gnome perl5
+USE_GNOME=	libxml2
+USE_CXXSTD=	c++11 # attempt to fix failure: Cubic_spline_calc.cpp:1107:5: error: ISO C++17 does not allow 'register' storage class specifier
+
 USE_GITHUB=	yes
 GH_ACCOUNT=	QWalk
 GH_PROJECT=	mainline
-USE_GNOME=	libxml2
 
 WRKSRC_SUBDIR=	src
 MAKE_ARGS=	INSTALLPATH=${STAGEDIR}${PREFIX}/bin
 
 .include <bsd.port.mk>