--- a/check-all.sh	Tue Feb 11 21:43:14 2025 +0100
+++ b/check-all.sh	Tue Feb 11 21:47:12 2025 +0100
@@ -15,7 +15,7 @@
 function perform_check_cxx
 {
   # we cannot mute the warnings, so throw every everything
-  if ! make check-cxx > /dev/null 2> /dev/null ; then
+  if ! make clean check-cxx > /dev/null 2> /dev/null ; then
     echo "fail."
   else
     echo "ok."