diff --git a/emulators/x16-emulator/Makefile b/emulators/x16-emulator/Makefile
index 9c371aed1431..433d3718c2db 100644
--- a/emulators/x16-emulator/Makefile
+++ b/emulators/x16-emulator/Makefile
@@ -1,35 +1,42 @@
 PORTNAME=	x16-emulator
 DISTVERSION=	r40
 CATEGORIES=	emulators
 
 MAINTAINER=	makc@FreeBSD.org
 COMMENT=	Emulator for the Commander X16 8-bit computer
 WWW=		https://github.com/commanderx16
 
 LICENSE=	BSD2CLAUSE
 LICENSE_FILE=	${WRKSRC}/LICENSE
 
 RUN_DEPENDS=	${DATADIR}/rom.bin:emulators/x16-rom
 
 USES=		compiler:c++11-lang gmake sdl
 
 USE_SDL=	sdl2
 USE_GITHUB=	yes
 GH_ACCOUNT=	commanderx16
 
 DESKTOP_ENTRIES=	"Commander X16" \
 			"" \
 			"" \
 			"x16emu" \
 			"" \
 			true
 
 PLIST_FILES=	bin/x16emu
 
+.include <bsd.port.options.mk>
+
 post-patch:
 	${REINPLACE_CMD} -e "s,%%PREFIX%%,${PREFIX}," ${WRKSRC}/src/main.c
+.if ${OPSYS} == FreeBSD && ( ${OSVERSION} >= 1400079 || ( ${OSVERSION} >= 1302505 && ${OSVERSION} < 1400000 ))
+	${REINPLACE_CMD} -e 's|^CFLAGS=|CFLAGS=-Wno-error=deprecated-non-prototype |g' \
+		${WRKSRC}/Makefile
+.endif
+
 
 do-install:
 	${INSTALL_PROGRAM} ${WRKSRC}/x16emu ${STAGEDIR}${PREFIX}/bin
 
 .include <bsd.port.mk>