diff --git a/devel/rubygem-concurrent-ruby-ext/Makefile b/devel/rubygem-concurrent-ruby-ext/Makefile
index e2f16ba8293f..90cda04607c3 100644
--- a/devel/rubygem-concurrent-ruby-ext/Makefile
+++ b/devel/rubygem-concurrent-ruby-ext/Makefile
@@ -1,17 +1,23 @@
 PORTNAME=	concurrent-ruby-ext
 PORTVERSION=	1.2.2
 CATEGORIES=	devel rubygems
 MASTER_SITES=	RG
 
 MAINTAINER=	sunpoet@FreeBSD.org
 COMMENT=	C extensions to optimize the concurrent-ruby
 WWW=		https://github.com/ruby-concurrency/concurrent-ruby
 
 LICENSE=	MIT
 LICENSE_FILE=	${WRKSRC}/LICENSE.txt
 
 RUN_DEPENDS=	rubygem-concurrent-ruby>=${PORTVERSION}<${PORTVERSION}_99:devel/rubygem-concurrent-ruby
 
 USES=		gem
 
+.include <bsd.port.options.mk>
+
+.if ${OPSYS} == FreeBSD && ( ${OSVERSION} >= 1400079 || ( ${OSVERSION} >= 1302505 && ${OSVERSION} < 1400000 ))
+CONFIGURE_ARGS+=	--with-cflags="-Wno-error=int-conversion"
+.endif
+
 .include <bsd.port.mk>