diff --git a/.circleci/config.yml b/.circleci/config.yml
index 3440ea6..06d5dc5 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -12,13 +12,13 @@ jobs:
       - checkout
       - restore_cache:
           keys:
-          - v1-dependencies-{{ checksum 'composer.json' }}
+          - v1-dependencies-{{ checksum "composer.json" }}
           - v1-dependencies-
       - run: composer install -n --prefer-dist
       - save_cache:
           paths:
             - ./vendor
-          key: v1-dependencies-{{ checksum 'composer.json' }}
+          key: v1-dependencies-{{ checksum "composer.json" }}
       - run: ./vendor/bin/phpunit --log-junit ~/phpunit/junit.xml
       - store_test_results:
           path: ~/phpunit