diff --git a/Makefile b/Makefile
index c10586b84fb..430d1fec170 100644
--- a/Makefile
+++ b/Makefile
@@ -18,6 +18,8 @@ BUILDDIR        = build
 SITEDIR         = /site
 VERSION         = testing
 
+# needed for Sphinx > 4.5?
+export LC_ALL=C.UTF-8
 
 # Put it first so that "make" without argument is like "make help".
 help: