--- a/kernel/conftest.sh
+++ b/kernel/conftest.sh
@@ -6,6 +6,10 @@
 SCRIPTDIR=`dirname $0`
 cd $SCRIPTDIR
 
+# translate_and_compile_header_files() expects the default locale
+# https://bugs.gentoo.org/698238
+export LC_ALL=C
+
 CC="$1"
 ARCH=$2
 ISYSTEM=`$CC -print-file-name=include 2> /dev/null`