diff --git a/.eslintrc.json b/.eslintrc.json
index 0f854e76..5d0c216b 100644
--- a/.eslintrc.json
+++ b/.eslintrc.json
@@ -32,6 +32,7 @@
         "no-prototype-builtins": "error",
         "no-shadow": ["error", {"builtinGlobals": false}],
         "no-undef": "error",
+        "no-undefined": "error",
         "no-underscore-dangle": ["error", {"allowAfterThis": true, "allowAfterSuper": false, "allowAfterThisConstructor": false}],
         "no-unexpected-multiline": "error",
         "no-unneeded-ternary": "error",