diff --git a/graphics/py-ueberzug/Makefile b/graphics/py-ueberzug/Makefile
index 979f7fa5fb8f..997b89a652b1 100644
--- a/graphics/py-ueberzug/Makefile
+++ b/graphics/py-ueberzug/Makefile
@@ -1,36 +1,37 @@
 PORTNAME=	ueberzug
 DISTVERSION=	18.1.8
 CATEGORIES=	graphics python
 PKGNAMEPREFIX=	${PYTHON_PKGNAMEPREFIX}
 
 MAINTAINER=	0mp@FreeBSD.org
 COMMENT=	Draw images on terminals with X11 child windows
 
 LICENSE=	GPLv3+
 LICENSE_FILE=	${WRKSRC}/LICENSE
 
 RUN_DEPENDS=	${PY_PILLOW} \
 		${PYTHON_PKGNAMEPREFIX}attrs>=18.2.0:devel/py-attrs@${PY_FLAVOR} \
 		${PYTHON_PKGNAMEPREFIX}docopt>=0:devel/py-docopt@${PY_FLAVOR} \
 		${PYTHON_PKGNAMEPREFIX}psutil>=0:sysutils/py-psutil@${PY_FLAVOR} \
 		${PYTHON_PKGNAMEPREFIX}xlib>=0:x11-toolkits/py-xlib@${PY_FLAVOR}
 
 USES=		localbase python:3.6+ shebangfix xorg
+USE_CSTD=	c99
 USE_GITHUB=	yes
 GH_ACCOUNT=	seebye
 USE_PYTHON=	autoplist concurrent distutils
 USE_XORG=	x11 xext
 SHEBANG_GLOB=	*.py *.sh
 
 PORTEXAMPLES=	fzfimg.sh mastodon.sh
 
 OPTIONS_DEFINE=	EXAMPLES
 
 post-install:
 	${STRIP_CMD} ${STAGEDIR}${PYTHON_SITELIBDIR}/Xshm.so
 
 post-install-EXAMPLES-on:
 	${MKDIR} ${STAGEDIR}${EXAMPLESDIR}
 	${INSTALL_DATA} ${WRKSRC}/examples/* ${STAGEDIR}${EXAMPLESDIR}
 
 .include <bsd.port.mk>