diff -purN a/m4/boost.m4 b/m4/boost.m4
--- a/m4/boost.m4	2020-07-30 00:20:40.000000000 +0200
+++ b/m4/boost.m4	2025-10-11 15:06:49.581067581 +0200
@@ -1023,11 +1023,13 @@ BOOST_DEFUN([String_Algo],
 # --------------------------------
 # Look for Boost.System.  For the documentation of PREFERRED-RT-OPT, see the
 # documentation of BOOST_FIND_LIB above.  This library was introduced in Boost
-# 1.35.0.
+# 1.35.0 and removed in 1.69.0
 BOOST_DEFUN([System],
-[BOOST_FIND_LIB([system], [$1],
+[if test $boost_major_version -lt 169; then
+  BOOST_FIND_LIB([system], [$1],
                 [boost/system/error_code.hpp],
                 [boost::system::error_code e; e.clear();])
+fi
 ])# BOOST_SYSTEM