diff --git a/devel/concurrencpp/Makefile b/devel/concurrencpp/Makefile
index 2ac84cc48431..c137acff6364 100644
--- a/devel/concurrencpp/Makefile
+++ b/devel/concurrencpp/Makefile
@@ -1,25 +1,27 @@
 PORTNAME=	concurrencpp
 DISTVERSIONPREFIX=	v.
 DISTVERSION=	0.1.3
 CATEGORIES=	devel
 
 MAINTAINER=	yuri@FreeBSD.org
 COMMENT=	C++ concurrency library: tasks, executors, timers, C++20 coroutines
 
 LICENSE=	MIT
 LICENSE_FILE=	${WRKSRC}/LICENSE.txt
 
+BROKEN_FreeBSD_12=	fatal error: 'semaphore' file not found (missing C++ include <semaphore>)
+
 USES=		cmake compiler:c++17-lang # should be compiler:c++20-lang
 
 USE_GITHUB=	yes
 GH_ACCOUNT=	David-Haim
 
 CMAKE_ON=	BUILD_SHARED_LIBS
 
 do-test: # same as recommended in https://github.com/David-Haim/concurrencpp#building-installing-and-testing
 	@cd ${WRKSRC} && \
 		${CMAKE_BIN} -S test -B build/test && \
 		${CMAKE_BIN} --build build/test && \
 		cd build/test && ctest .
 
 .include <bsd.port.mk>