--- configure.ac.orig	2021-11-25 09:41:46 UTC
+++ configure.ac
@@ -11,6 +11,7 @@ AC_DEFINE_UNQUOTED(PLATFORM, "$ac_cv_host",
                    [the type of system on which the package will run.])
 
 # Checks for programs.
+AC_PROG_CPP
 AC_PROG_CC
 AC_PROG_GCC_TRADITIONAL
 AC_PROG_INSTALL