diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index cc93fdb0ef8e865062be887c464a2e7bb8dda45e..b7cf883cc9b397989942eb2ef1a557cfc77ea4df 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -2,5 +2,5 @@ build-doc:
     image: gitlab-research.centralesupelec.fr:4567/2017bentrioum/markovprocesses.jl/julia
     stage: build
     script:
-        - "julia --project=docs/ -e 'using Pkg; Pkg.develop(PackageSpec(path=pwd(), subdir="core")); Pkg.instantiate()'"
+        - "julia --project=docs/ -e 'using Pkg; Pkg.develop(PackageSpec(path=pwd(), subdir=\"core\")); Pkg.instantiate()'"
         - "julia --project=docs/ docs/make.jl"