--- multimedia/libgav1/Makefile	(revision 557852)
+++ multimedia/libgav1/Makefile	(working copy)
@@ -3,6 +3,7 @@ 
 PORTNAME=	libgav1
 DISTVERSIONPREFIX=	v
 DISTVERSION=	0.16.0
+PORTREVISION=	1
 CATEGORIES=	multimedia
 
 MAINTAINER=	jbeich@FreeBSD.org
@@ -12,7 +13,7 @@ 
 
 LIB_DEPENDS=	libabsl_synchronization.so:devel/abseil
 
-USES=		cmake compiler:c++11-lib localbase:ldflags
+USES=		cmake compiler:c++17-lang localbase:ldflags
 USE_GITHUB=	yes
 USE_LDCONFIG=	yes
 GH_ACCOUNT=	jbeich # mirror
--- multimedia/libgav1/files/patch-CMakeLists.txt	(revision 557852)
+++ multimedia/libgav1/files/patch-CMakeLists.txt	(working copy)
@@ -1,7 +1,19 @@ 
+- Sync -std= with devel/abseil to match ABI
 - Avoid leaking abseil dependency to shared library consumers
 
 --- CMakeLists.txt.orig	2020-07-15 02:27:54 UTC
 +++ CMakeLists.txt
+@@ -16,8 +16,8 @@
+ cmake_minimum_required(VERSION 3.7.1 FATAL_ERROR)
+ 
+ # libgav1 requires C++11.
+-set(CMAKE_CXX_STANDARD 11)
+-set(ABSL_CXX_STANDARD 11)
++set(CMAKE_CXX_STANDARD 17)
++set(ABSL_CXX_STANDARD 17)
+ 
+ project(libgav1 CXX)
+ 
 @@ -107,8 +107,11 @@ if(NOT "${LIBGAV1_EXE_LINKER_FLAGS}" STREQUAL "")
    separate_arguments(LIBGAV1_EXE_LINKER_FLAGS)
  endif()