diff --git a/x11-wm/wlmaker/Makefile b/x11-wm/wlmaker/Makefile
index 97d4b47a1603..f7bcf8d18d99 100644
--- a/x11-wm/wlmaker/Makefile
+++ b/x11-wm/wlmaker/Makefile
@@ -1,47 +1,50 @@
 PORTNAME=	wlmaker
 DISTVERSIONPREFIX=	v
 DISTVERSION=	0.1-444
 DISTVERSIONSUFFIX=	-ga388205
 CATEGORIES=	x11-wm wayland
 
 MAINTAINER=	jbeich@FreeBSD.org
 COMMENT=	Wayland compositor inspired by Window Maker
 WWW=		https://github.com/phkaeser/wlmaker
 
 LICENSE=	APACHE20
 
 BUILD_DEPENDS=	evdev-proto>0:devel/evdev-proto \
 		wayland-protocols>=1.31:graphics/wayland-protocols
 LIB_DEPENDS=	libepoll-shim.so:devel/libepoll-shim \
 		libwayland-server.so:graphics/wayland \
 		libwlroots.so:x11-toolkits/wlroots \
 		libxkbcommon.so:x11/libxkbcommon
 RUN_DEPENDS=	foot:x11/foot
 
 USES=		cmake compiler:c11 gnome pkgconfig
 USE_GITHUB=	yes
 USE_GNOME=	cairo
 GH_ACCOUNT=	phkaeser
 GH_TUPLE=	phkaeser:libbase:66a3992:libbase/submodules/libbase
 PLIST_FILES=	bin/${PORTNAME} \
 		bin/wlmclock \
 		share/icons/${PORTNAME}/chrome-48x48.png \
 		share/icons/${PORTNAME}/clip-48x48.png \
 		share/icons/${PORTNAME}/firefox-48x48.png \
 		share/icons/${PORTNAME}/terminal-48x48.png \
 		${NULL}
 
 post-patch:
 # Drop dependency on unreleased version of libwayland
 	@${REINPLACE_CMD} -e 's/1\.22\.90/1.22.0/' \
 		${WRKSRC}/CMakeLists.txt
 # Respect PREFIX for icons
 	@${REINPLACE_CMD} 's,/usr/share,${DATADIR:H},' \
 		${WRKSRC}/src/decorations.c
 # Respect LOCALBASE for apps and use open source Chrome
 	@${REINPLACE_CMD} -e 's,/usr/bin,${LOCALBASE}/bin,' \
 		 -e 's/google-chrome/chrome/' \
 		${WRKSRC}/src/dock.c \
 		${WRKSRC}/src/${PORTNAME}.c
+# https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=276743
+	@${GREP} -Flr _POSIX_C_SOURCE ${WRKSRC} | ${XARGS} ${REINPLACE_CMD} \
+		'/_POSIX_C_SOURCE/d'
 
 .include <bsd.port.mk>