diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 0b5dbf7833903e551a29af76bdf415acc1216b93..04027837edca75f70b9f3a453cbb9793b0242054 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -5,7 +5,7 @@ variables:
   DOCKER_REV: e517150438cd9df9564fb91adc4b42e2667b2bc1
 
 build-pdf:
-  "registry.gitlab.haskell.org/ghc/ci-images/x86_64-linux-deb9:$DOCKER_REV"
+  image: "registry.gitlab.haskell.org/ghc/ci-images/x86_64-linux-deb9:$DOCKER_REV"
   # image: "ocaml/opam2:latest"
   
   script: