diff --git a/m4/check-libc-compat.m4 b/m4/check-libc-compat.m4
index afced95..a806cbe 100644
--- a/m4/check-libc-compat.m4
+++ b/m4/check-libc-compat.m4
@@ -12,8 +12,9 @@ fi
 ])
 
 AC_DEFUN([CHECK_SYSCALL_COMPAT], [
-AC_CHECK_FUNCS([accept4 pipe2 pledge poll socketpair])
+AC_CHECK_FUNCS([accept4 adjtimex pipe2 pledge poll socketpair])
 AM_CONDITIONAL([HAVE_ACCEPT4], [test "x$ac_cv_func_accept4" = xyes])
+AM_CONDITIONAL([HAVE_ADJTIMEX], [test "x$ac_cv_func_adjtimex" = xyes])
 AM_CONDITIONAL([HAVE_PIPE2], [test "x$ac_cv_func_pipe2" = xyes])
 AM_CONDITIONAL([HAVE_PLEDGE], [test "x$ac_cv_func_pledge" = xyes])
 AM_CONDITIONAL([HAVE_POLL], [test "x$ac_cv_func_poll" = xyes])