Index: head/x11-toolkits/py-tktreectrl/Makefile
===================================================================
--- head/x11-toolkits/py-tktreectrl/Makefile	(revision 567194)
+++ head/x11-toolkits/py-tktreectrl/Makefile	(revision 567195)
@@ -1,25 +1,26 @@
 # Created by: Andrew Pantyukhin <infofarmer@FreeBSD.org>
 # $FreeBSD$
 
 PORTNAME=	tktreectrl
 DISTVERSION=	2.0.2
 CATEGORIES=	x11-toolkits tk python
 MASTER_SITES=	SF/tkintertreectrl/TkinterTreectrl-${PORTVERSION:R}/
 PKGNAMEPREFIX=	${PYTHON_PKGNAMEPREFIX}
 DISTNAME=	TkinterTreectrl-${DISTVERSION}
 
 MAINTAINER=	sunpoet@FreeBSD.org
 COMMENT=	TkTreectrl Python bindings
 
 LICENSE=	PD
 
 # x11-toolkits/tktreectrl does not provide libtreectrl.so
 LIB_DEPENDS=	libtreectrl.so.1:x11-toolkits/tktreectrl
 RUN_DEPENDS=	${PYTHON_PKGNAMEPREFIX}Pmw>=0:x11-toolkits/py-Pmw@${PY_FLAVOR} \
 		${PYTHON_PKGNAMEPREFIX}tkinter>=0:x11-toolkits/py-tkinter@${PY_FLAVOR}
 
 USES=		python:3.6+ tk:run zip
-USE_PYTHON=	autoplist distutils
+USE_PYTHON=	autoplist concurrent distutils
+
 NO_ARCH=	yes
 
 .include <bsd.port.mk>