diff --git a/lib/index.js b/lib/index.js
index <HASH>..<HASH> 100644
--- a/lib/index.js
+++ b/lib/index.js
@@ -1,3 +1,5 @@
+// SPDX-License-Identifier: MIT
+
 var debug = require('debug')('metalsmith-convert'),
     path = require('path'),
     minimatch = require('minimatch'),
Added SPDX license identifier