diff --git a/math/openfst/Makefile b/math/openfst/Makefile
index 1e14c1e7ef71..4869fd33156c 100644
--- a/math/openfst/Makefile
+++ b/math/openfst/Makefile
@@ -1,24 +1,25 @@
 # Created by: Dmitry Sivachenko <mitya@yandex-team.ru>
 # $FreeBSD$
 
 PORTNAME=	openfst
 PORTVERSION=	1.5.4
 CATEGORIES=	math
 MASTER_SITES=	http://www.openfst.org/twiki/pub/FST/FstDownload/
 
 MAINTAINER=	demon@FreeBSD.org
 COMMENT=	Library for working with weighted finite-state transducers (FSTs)
 
 LICENSE=	APACHE20
 
 BROKEN_powerpc64=	Does not build
 BROKEN_sparc64=	Does not build: fails to compile symbol-table-ops.cc
 
 USES=		compiler:c++11-lib libtool python:2
 USE_LDCONFIG=	${LOCALBASE}/lib/fst
 GNU_CONFIGURE=	yes
 CONFIGURE_ARGS+=--enable-bin --enable-compact-fsts --enable-compress --enable-const-fsts --enable-far --enable-linear-fsts --enable-lookahead-fsts --enable-mpdt --enable-ngram-fsts --enable-pdt --enable-python
+CFLAGS+=	-D_GLIBCXX_USE_C99 # XXX ports/193528
 LDFLAGS+=	"-L${LOCALBASE}/lib"
 MAKE_ENV+=	PYTHON=${PYTHON_CMD}
 
 .include <bsd.port.mk>