diff --git a/devel/libphonenumber/Makefile b/devel/libphonenumber/Makefile
index 3848319e39d6..5010a463b401 100644
--- a/devel/libphonenumber/Makefile
+++ b/devel/libphonenumber/Makefile
@@ -1,32 +1,36 @@
 PORTNAME=	libphonenumber
 DISTVERSIONPREFIX=	v
-DISTVERSION=	8.13.20
+DISTVERSION=	8.13.21
 CATEGORIES=	devel
 
 MAINTAINER=	kde@FreeBSD.org
 COMMENT=	Library for parsing, formatting, and validating phone numbers
 WWW=		https://github.com/google/libphonenumber
 
 LICENSE=	APACHE20
 
 BUILD_DEPENDS=	googletest>0:devel/googletest
 LIB_DEPENDS=	libabsl_strings.so:devel/abseil \
 		libboost_atomic.so:devel/boost-libs \
 		libicui18n.so:devel/icu \
 		libprotobuf.so:devel/protobuf
 
 USES=		cmake:noninja compiler:c++17-lang pkgconfig
+# Workaround CMAKE_ARGS+=-DABSL_PROPAGATE_CXX_STD:BOOL=ON not being set in the
+# devel/abseil Makefile. As of version 8.13.21, libphonenumber no longer sets
+# the C++ dialect and expects to inherit it from abseil.
+USE_CXXSTD=	c++17
 USE_GITHUB=	yes
 GH_ACCOUNT=	google
 
 CMAKE_ON=	USE_STD_MAP
 CMAKE_OFF=	REGENERATE_METADATA \
 		BUILD_TESTING
 
 WRKSRC_SUBDIR=	cpp
 
 MAKE_JOBS_UNSAFE=	yes
 
 PLIST_SUB=	SHLIB_FULL=${PORTVERSION:R} SHLIB_SHORT=${PORTVERSION:R:R}
 
 .include <bsd.port.mk>
diff --git a/devel/libphonenumber/distinfo b/devel/libphonenumber/distinfo
index 3c93979d3876..2bb39b189d85 100644
--- a/devel/libphonenumber/distinfo
+++ b/devel/libphonenumber/distinfo
@@ -1,3 +1,3 @@
-TIMESTAMP = 1694524567
-SHA256 (google-libphonenumber-v8.13.20_GH0.tar.gz) = 81ac6371367912463c612a4b4a6942ab10b7faf800b8dc026d6db3d157bed9b5
-SIZE (google-libphonenumber-v8.13.20_GH0.tar.gz) = 14810379
+TIMESTAMP = 1695283658
+SHA256 (google-libphonenumber-v8.13.21_GH0.tar.gz) = bca757a8e04849c8158bbbc243c500699daa7601d1fd23a1277fc2643188b44b
+SIZE (google-libphonenumber-v8.13.21_GH0.tar.gz) = 14809594
diff --git a/devel/libphonenumber/files/patch-CMakeLists.txt b/devel/libphonenumber/files/patch-CMakeLists.txt
index 84b597363642..f91ae68395d1 100644
--- a/devel/libphonenumber/files/patch-CMakeLists.txt
+++ b/devel/libphonenumber/files/patch-CMakeLists.txt
@@ -1,20 +1,11 @@
---- CMakeLists.txt.orig	2023-01-06 10:17:24 UTC
+--- CMakeLists.txt.orig	2023-09-19 04:20:31 UTC
 +++ CMakeLists.txt
-@@ -20,7 +20,7 @@ project (libphonenumber VERSION 8.13.0)
- 
- # Pick the C++ standard to compile with.
- # Abseil currently supports C++11, C++14, and C++17.
--set(CMAKE_CXX_STANDARD 11 CACHE STRING "C++ standard used to compile this project")
-+set(CMAKE_CXX_STANDARD 17 CACHE STRING "C++ standard used to compile this project")
- set(CMAKE_CXX_STANDARD_REQUIRED ON)
- set(CMAKE_POSITION_INDEPENDENT_CODE TRUE)
- 
-@@ -106,7 +106,7 @@ endif ()
+@@ -100,7 +100,7 @@ endif ()
  endif ()
  
  # Find all the required libraries and programs.
 -find_package(absl)
 +find_package(absl REQUIRED)
  
  if(NOT absl_FOUND)
    # Overide abseil install rules for subprojects
diff --git a/devel/libphonenumber/files/patch-tools_CMakeLists.txt b/devel/libphonenumber/files/patch-tools_CMakeLists.txt
deleted file mode 100644
index 1f2c04eb002b..000000000000
--- a/devel/libphonenumber/files/patch-tools_CMakeLists.txt
+++ /dev/null
@@ -1,18 +0,0 @@
-This patch applies from WRKSRC_SUBDIR, ie. from cpp/ , but even
-when building in that subdir, the tools/ directory is built
-as well. That is why the patch applies to ..
-
-- use system abseil instead of fetching it on our own.
-- force C++17 because abseil has it, too.
-
---- ../tools/cpp/CMakeLists.txt.orig	2022-01-11 10:41:37.000000000 +0100
-+++ ../tools/cpp/CMakeLists.txt	2022-01-22 17:06:39.284013000 +0100
-@@ -18,7 +18,7 @@
- 
- # Pick the C++ standard to compile with.
- # Abseil currently supports C++11, C++14, and C++17.
--set(CMAKE_CXX_STANDARD 11)
-+set(CMAKE_CXX_STANDARD 17)
- set(CMAKE_CXX_STANDARD_REQUIRED ON)
- 
- project (generate_geocoding_data)