diff --git a/src/librustdoc/html/static/.eslintrc.js b/src/librustdoc/html/static/.eslintrc.js
index f98a6c01fe96..f153c9a714f8 100644
--- a/src/librustdoc/html/static/.eslintrc.js
+++ b/src/librustdoc/html/static/.eslintrc.js
@@ -68,5 +68,6 @@ module.exports = {
         "no-dupe-args": "error",
         "no-dupe-else-if": "error",
         "no-dupe-keys": "error",
+        "no-duplicate-case": "error",
     }
 };