diff --git a/packages/@vue/cli-service/lib/options.js b/packages/@vue/cli-service/lib/options.js
index 340369c4d5..27fd698a45 100644
--- a/packages/@vue/cli-service/lib/options.js
+++ b/packages/@vue/cli-service/lib/options.js
@@ -15,6 +15,7 @@ const schema = createSchema(joi => joi.object({
 
   // css
   css: joi.object({
+    camelCase: joi.boolean().allow(['dashes', 'only', 'dashesOnly']),
     modules: joi.boolean(),
     extract: joi.boolean(),
     localIdentName: joi.string(),