diff --git a/package.json b/package.json
index 363328c..b34c22f 100644
--- a/package.json
+++ b/package.json
@@ -39,6 +39,7 @@
     "blue-tape": "^1.0.0",
     "clone": "^2.1.1",
     "coveralls": "^3.0.0",
+    "mkdirp": "^0.5.1",
     "nyc": "^11.4.1",
     "rimraf": "^2.6.2",
     "xo": "^0.18.2"