diff --git a/cad/openscad-devel/Makefile b/cad/openscad-devel/Makefile
index 65ad017d2d1d..1845938d6d99 100644
--- a/cad/openscad-devel/Makefile
+++ b/cad/openscad-devel/Makefile
@@ -14,8 +14,6 @@ COMMENT=	Programmer's solid 3D CAD modeller
 LICENSE=	GPLv2+
 LICENSE_FILE=	${WRKSRC}/COPYING
 
-BROKEN_FreeBSD_10=      Missing __cxa_thread_atexit
-
 BUILD_DEPENDS=	${LOCALBASE}/bin/flex:textproc/flex \
 		${LOCALBASE}/include/boost/tuple/tuple.hpp:devel/boost-libs
 LIB_DEPENDS=	libgmp.so:math/gmp \
@@ -41,7 +39,7 @@ USE_QT4=	corelib gui opengl moc_build uic_build rcc_build
 PLIST_SUB=	PORTVERSION=${PORTVERSION}
 QMAKE_ENV=	EIGENDIR=${LOCALBASE}/include/eigen3
 QMAKE_ARGS+=	VERSION=${PORTVERSION} \
-		EXPERIMENTAL=yes \
+		CONFIG+="experimental" \
 		QMAKE_LEX=${LOCALBASE}/bin/flex \
 		QMAKE_YAC=${LOCALBASE}/bin/bison
 
@@ -49,4 +47,10 @@ post-patch:
 	@${REINPLACE_CMD} -e 's,share/man,man,' \
 		${WRKSRC}/openscad.pro
 
+.include <bsd.port.options.mk>
+
+.if ${OPSYS} == FreeBSD && ${OSVERSION} < 1003506
+BROKEN=		no __cxa_thread_atexit() support in FreeBSD libc < 10.4
+.endif
+
 .include <bsd.port.mk>
diff --git a/cad/openscad-devel/files/patch-openscad.pro b/cad/openscad-devel/files/patch-openscad.pro
index e261d4978ac7..f764f845f1fa 100644
--- a/cad/openscad-devel/files/patch-openscad.pro
+++ b/cad/openscad-devel/files/patch-openscad.pro
@@ -1,10 +1,5 @@
 --- openscad.pro.orig	2018-04-19 22:08:08 UTC
 +++ openscad.pro
-@@ -1,3 +1,4 @@
-+CONFIG+=experimental
- # Environment variables which can be set to specify library locations:
- # MPIRDIR
- # MPFRDIR
 @@ -105,6 +106,10 @@ mingw* {
  CONFIG += qt
  QT += widgets concurrent