diff --git a/package.json b/package.json
index 5afe49f19..bf9e3fe29 100644
--- a/package.json
+++ b/package.json
@@ -13,7 +13,7 @@
     "bower": "bower install --allow-root --config.interactive=false",
     "build:watch": "concurrent \"npm run build:css:watch\" \"npm run build:js:watch\"",
     "build": "npm run build:js && npm run build:css",
-    "build:css": "concurrent 'npm run build:css:ipython' 'npm run build:css:style'",
+    "build:css": "concurrent \"npm run build:css:ipython\" \"npm run build:css:style\"",
     "build:css:ipython": "lessc --include-path=notebook/static notebook/static/style/ipython.less notebook/static/style/ipython.min.css",
     "build:css:style": "lessc --include-path=notebook/static notebook/static/style/style.less notebook/static/style/style.min.css",
     "build:css:watch": "echo Not implemented yet...",