Index: head/audio/ft2play/Makefile
===================================================================
--- head/audio/ft2play/Makefile	(revision 566825)
+++ head/audio/ft2play/Makefile	(revision 566826)
@@ -1,34 +1,35 @@
 # Created by: Emanuel Haupt <ehaupt@FreeBSD.org>
 # $FreeBSD$
 
 PORTNAME=	ft2play
 DISTVERSION=	g20210124
 CATEGORIES=	audio
 
 MAINTAINER=	ehaupt@FreeBSD.org
 COMMENT=	Bit-accurate C port of Fasttracker's XM replayer
 
 LICENSE=	BSD3CLAUSE
 LICENSE_FILE=	${WRKSRC}/LICENSE
 
 USES=		sdl
+USE_CSTD=	c99
 USE_GITHUB=	yes
 GH_ACCOUNT=	8bitbubsy
 GH_TAGNAME=	5730b16
 USE_SDL=	sdl2
 
 CFLAGS+=	-DAUDIODRIVER_SDL -DNDEBUG `sdl2-config --cflags`
 LDFLAGS+=	-lm -lpthread `sdl2-config --libs`
 
 PLIST_FILES=	bin/ft2play
 
 do-build:
 	${CC} ${CFLAGS} ${LDFLAGS} ${WRKSRC}/audiodrivers/sdl/*.c \
 		${WRKSRC}/*.c ${WRKSRC}/ft2play/src/*.c \
 		-o ${WRKSRC}/ft2play/release/other/ft2play
 
 do-install:
 	${INSTALL_PROGRAM} ${WRKSRC}/ft2play/release/other/ft2play \
 		${STAGEDIR}${PREFIX}/bin
 
 .include <bsd.port.mk>