--- /dev/null
+diff -u -r ../flex-2.6.4/Makefile.in ./Makefile.in
+--- ../flex-2.6.4/Makefile.in 2017-05-06 16:49:09.000000000 +0200
++++ ./Makefile.in 2018-04-29 23:46:48.128733975 +0200
+@@ -453,7 +453,6 @@
+ doc \
+ examples \
+ po \
+- tests \
+ tools
+
+ all: all-recursive