Index: math/ntl/Makefile
===================================================================
--- math/ntl/Makefile	(revision 479914)
+++ math/ntl/Makefile	(working copy)
@@ -3,6 +3,7 @@
 
 PORTNAME=	ntl
 PORTVERSION=	11.3.0
+PORTREVISION=	1
 CATEGORIES=	math
 MASTER_SITES=	http://www.shoup.net/ntl/
 
@@ -12,7 +13,7 @@
 LICENSE=	LGPL21+
 LICENSE_FILE=	${WRKSRC}/../doc/copying.txt
 
-USES=		perl5 libtool
+USES=		compiler:c11 libtool perl5
 USE_LDCONFIG=	yes
 USE_PERL5=	build
 HAS_CONFIGURE=	yes