diff --git a/styleguide/package.json b/styleguide/package.json
index 377f9da7b..6879fabaf 100644
--- a/styleguide/package.json
+++ b/styleguide/package.json
@@ -8,7 +8,7 @@
     "lint": "vue-cli-service lint",
     "dev": "npm-run-all --parallel theo:onchange theo servedev",
     "servedev": "vue-cli-service serve --open",
-    "build:lib": "yarn theo && BUILD=library vue-cli-service build --target lib --name system ./src/library.js",
+    "build:lib": "yarn theo && cross-env BUILD=library vue-cli-service build --target lib --name system ./src/library.js",
     "theo": "theo ./src/system/tokens/tokens.yml --transform web --format map.scss,scss,raw.json,json --dest ./src/system/tokens/generated",
     "theo:onchange": "onchange \"./src/system/tokens/*.yml\" -- npm run theo",
     "test:unit": "vue-cli-service test:unit"
@@ -31,6 +31,7 @@
     "cheerio": "^1.0.0-rc.2",
     "clone-deep": "^4.0.0",
     "codemirror": "^5.39.2",
+    "cross-env": "^5.2.0",
     "dot-prop": "^4.2.0",
     "lodash": "^4.17.10",
     "markdown-it": "^8.4.2",
diff --git a/styleguide/yarn.lock b/styleguide/yarn.lock
index 993a17553..dcde904cd 100644
--- a/styleguide/yarn.lock
+++ b/styleguide/yarn.lock
@@ -3033,6 +3033,13 @@ create-hmac@^1.1.0, create-hmac@^1.1.2, create-hmac@^1.1.4:
     safe-buffer "^5.0.1"
     sha.js "^2.4.8"
 
+cross-env@^5.2.0:
+  version "5.2.0"
+  resolved "https://registry.yarnpkg.com/cross-env/-/cross-env-5.2.0.tgz#6ecd4c015d5773e614039ee529076669b9d126f2"
+  dependencies:
+    cross-spawn "^6.0.5"
+    is-windows "^1.0.0"
+
 cross-spawn@^3.0.0:
   version "3.0.1"
   resolved "https://registry.yarnpkg.com/cross-spawn/-/cross-spawn-3.0.1.tgz#1256037ecb9f0c5f79e3d6ef135e30770184b982"
@@ -3048,7 +3055,7 @@ cross-spawn@^5.0.1, cross-spawn@^5.1.0:
     shebang-command "^1.2.0"
     which "^1.2.9"
 
-cross-spawn@^6.0.0, cross-spawn@^6.0.4, cross-spawn@~6.0.0:
+cross-spawn@^6.0.0, cross-spawn@^6.0.4, cross-spawn@^6.0.5, cross-spawn@~6.0.0:
   version "6.0.5"
   resolved "https://registry.yarnpkg.com/cross-spawn/-/cross-spawn-6.0.5.tgz#4a5ec7c64dfae22c3a14124dbacdee846d80cbc4"
   dependencies:
@@ -5374,7 +5381,7 @@ is-whitespace@^0.3.0:
   version "0.3.0"
   resolved "https://registry.yarnpkg.com/is-whitespace/-/is-whitespace-0.3.0.tgz#1639ecb1be036aec69a54cbb401cfbed7114ab7f"
 
-is-windows@^1.0.2:
+is-windows@^1.0.0, is-windows@^1.0.2:
   version "1.0.2"
   resolved "https://registry.yarnpkg.com/is-windows/-/is-windows-1.0.2.tgz#d1850eb9791ecd18e6182ce12a30f396634bb19d"