diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 128f6f6..5df7ca5 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -18,7 +18,7 @@ build:
     - docker build --pull -t "$CONTAINER_TEST_IMAGE" .
     - docker push "$CONTAINER_TEST_IMAGE"
   cache:
-    key: 2
+    key: "2"
 
 release-image:
   stage: release