diff --git a/packages/eslint-plugin/package.json b/packages/eslint-plugin/package.json
index 53d21ecf3da..363f96e7dba 100644
--- a/packages/eslint-plugin/package.json
+++ b/packages/eslint-plugin/package.json
@@ -39,6 +39,7 @@
     "@typescript-eslint/experimental-utils": "1.8.0",
     "@typescript-eslint/parser": "1.8.0",
     "eslint-utils": "^1.3.1",
+    "functional-red-black-tree": "^1.0.1",
     "regexpp": "^2.0.1",
     "requireindex": "^1.2.0",
     "tsutils": "^3.7.0"