diff --git a/packages/@opticss/demo-app/package.json b/packages/@opticss/demo-app/package.json
index a1144700..20949618 100644
--- a/packages/@opticss/demo-app/package.json
+++ b/packages/@opticss/demo-app/package.json
@@ -59,7 +59,7 @@
     "babel-preset-env": "^1.6.0",
     "browserify": "amiller-gh/browserify",
     "gzip-js": "^0.3.2",
-    "mkdirp": "^0.5.1",
+    "mkdirp": "^1.0.0",
     "moo": "^0.5.0",
     "nearley": "^2.10.3",
     "rimraf": "^2.6.2",
diff --git a/yarn.lock b/yarn.lock
index c772a8fb..a19fbe43 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -6122,6 +6122,11 @@ mkdirp@0.5.1, mkdirp@0.5.x, "mkdirp@>=0.5 0", mkdirp@^0.5.0, mkdirp@^0.5.1, mkdi
   dependencies:
     minimist "0.0.8"
 
+mkdirp@^1.0.0:
+  version "1.0.2"
+  resolved "https://registry.yarnpkg.com/mkdirp/-/mkdirp-1.0.2.tgz#5ccd93437619ca7050b538573fc918327eba98fb"
+  integrity sha512-N2REVrJ/X/jGPfit2d7zea2J1pf7EAR5chIUcfHffAZ7gmlam5U65sAm76+o4ntQbSRdTjYf7qZz3chuHlwXEA==
+
 mocha-typescript@^1.1.9:
   version "1.1.17"
   resolved "https://registry.yarnpkg.com/mocha-typescript/-/mocha-typescript-1.1.17.tgz#f78b29ad4f87fce8c25f657883e3eca39fb026c9"
@@ -7407,10 +7412,10 @@ preserve@^0.2.0:
   resolved "https://registry.yarnpkg.com/preserve/-/preserve-0.2.0.tgz#815ed1f6ebc65926f865b310c0713bcb3315ce4b"
   integrity sha1-gV7R9uvGWSb4ZbMQwHE7yzMVzks=
 
-prettier@1.17.0:
-  version "1.17.0"
-  resolved "https://registry.yarnpkg.com/prettier/-/prettier-1.17.0.tgz#53b303676eed22cc14a9f0cec09b477b3026c008"
-  integrity sha512-sXe5lSt2WQlCbydGETgfm1YBShgOX4HxQkFPvbxkcwgDvGDeqVau8h+12+lmSVlP3rHPz0oavfddSZg/q+Szjw==
+prettier@1.17.1:
+  version "1.17.1"
+  resolved "https://registry.yarnpkg.com/prettier/-/prettier-1.17.1.tgz#ed64b4e93e370cb8a25b9ef7fef3e4fd1c0995db"
+  integrity sha512-TzGRNvuUSmPgwivDqkZ9tM/qTGW9hqDKWOE9YHiyQdixlKbv7kvEqsmDPrcHJTKwthU774TQwZXVtaQ/mMsvjg==
 
 pretty-bytes@^5.0.0:
   version "5.3.0"