Index: zxing-cpp-2.2.1/CMakeLists.txt
===================================================================
--- zxing-cpp-2.2.1.orig/CMakeLists.txt
+++ zxing-cpp-2.2.1/CMakeLists.txt
@@ -1,4 +1,4 @@
-cmake_minimum_required(VERSION 3.15)
+cmake_minimum_required(VERSION 3.5)
 
 project(ZXing)
 
@@ -37,9 +37,6 @@ if (BUILD_SHARED_LIBS)
     set (CMAKE_WINDOWS_EXPORT_ALL_SYMBOLS ON)
 endif()
 
-if (NOT CMAKE_CXX_STANDARD)
-    set (CMAKE_CXX_STANDARD 17)
-endif()
 if (NOT CMAKE_CXX_EXTENSIONS)
     set (CMAKE_CXX_EXTENSIONS OFF)
 endif()
Index: zxing-cpp-2.2.1/core/CMakeLists.txt
===================================================================
--- zxing-cpp-2.2.1.orig/core/CMakeLists.txt
+++ zxing-cpp-2.2.1/core/CMakeLists.txt
@@ -1,4 +1,4 @@
-cmake_minimum_required(VERSION 3.15)
+cmake_minimum_required(VERSION 3.5)
 
 project (ZXing VERSION "2.2.1")
 set (ZXING_SONAME 3) # see https://github.com/zxing-cpp/zxing-cpp/issues/333
@@ -464,8 +464,6 @@ if (COMPILER_NEEDS_FLOAT_STORE)
     )
 endif()
 
-target_compile_features(ZXing PUBLIC cxx_std_17)
-
 target_link_libraries (ZXing PRIVATE Threads::Threads)
 
 add_library(ZXing::ZXing ALIAS ZXing)