diff --git a/etc/config.sub b/etc/config.sub
new file mode 100644
index 0000000..1c766af
--- /dev/null
+++ b/etc/config.sub
@@ -0,0 +1,5 @@
+# assume a correct target input: this should always be the case
+# in the context of midipix_build; then, for compatibility, output
+# the target name.
+
+echo "$1"