https://github.com/google/libphonenumber/pull/3903

--- CMakeLists.txt.orig	2026-09-09 10:47:03 UTC
+++ CMakeLists.txt
@@ -145,7 +145,7 @@ if (USE_BOOST)
   if (WIN32)
     set (Boost_USE_STATIC_LIBS ON)
   endif ()
-  find_package (Boost 1.40.0 COMPONENTS date_time system thread)
+  find_package (Boost 1.40.0 COMPONENTS date_time thread OPTIONAL_COMPONENTS system)
   if (NOT Boost_FOUND)
     print_error ("Boost Date_Time/System/Thread" "Boost")
   endif ()