diff --git a/.circleci/config.yml b/.circleci/config.yml
index 16c83a61..1f7f9081 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -2,12 +2,12 @@ version: 2
 jobs:
   build:
     docker:
-      - image: circleci/node:latest
+      - image: circleci/node:8
     steps:
       - checkout
       - restore_cache:
           keys:
-          - dependencies-{{ checksum "package.json" }}
+          - dependencies-{{ checksum "yarn.lock" }}
           # fallback to using the latest cache if no exact match is found
           - dependencies-
       - run:
@@ -16,7 +16,7 @@ jobs:
       - save_cache:
           paths:
             - node_modules
-          key: dependencies-{{ checksum "package.json" }}
+          key: dependencies-{{ checksum "yarn.lock" }}
       - run:
           name: Check Prettier, ESLint, Flow
           command: yarn ci-check
diff --git a/package.json b/package.json
index 9ec03382..65cc1e8e 100644
--- a/package.json
+++ b/package.json
@@ -62,7 +62,7 @@
     "unist-util-visit": "^1.1.3"
   },
   "engines": {
-    "node": ">=8.4.0"
+    "node": "^8.4.0"
   },
   "homepage": "https://reactjs.org/",
   "keywords": [