diff --git a/libqpdf.pc.in b/libqpdf.pc.in
index 1a809f8..6f0ebe9 100644
--- a/libqpdf.pc.in
+++ b/libqpdf.pc.in
@@ -8,4 +8,4 @@ Description: PDF transformation library
 Version: @PROJECT_VERSION@
 Requires.private: zlib, libjpeg@CRYPTO_PKG@
 Libs: -L${libdir} -lqpdf
-Cflags: -I${includedir}
+Cflags: -I${includedir} -std=c++20
diff --git a/pkg-test/CMakeLists.txt b/pkg-test/CMakeLists.txt
index 36257f2..99c75ec 100644
--- a/pkg-test/CMakeLists.txt
+++ b/pkg-test/CMakeLists.txt
@@ -1,5 +1,6 @@
 cmake_minimum_required(VERSION 3.10)
 project(qpdf-version LANGUAGES CXX)
+set(CMAKE_CXX_STANDARD 20)
 find_package(qpdf)
 add_executable(qpdf-version qpdf-version.cc)
 target_link_libraries(qpdf-version qpdf::libqpdf)