diff --git a/package.json b/package.json
index b6bb5ca..ef56a12 100644
--- a/package.json
+++ b/package.json
@@ -83,6 +83,7 @@
   "dependencies": {
     "js-writer": "^1.3.0",
     "magicpen-prism": "^2.4.0",
+    "mkdirp": "^1.0.4",
     "unexpected-htmllike": "^2.2.0",
     "unexpected-htmllike-jsx-adapter": "^1.0.3",
     "unexpected-htmllike-raw-adapter": "^1.0.1",