diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 313af893aff5539e9920b00db9f7206f1c07eee2..56f605cbabd0e395381e8a71d46a2ada022ff481 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -6,6 +6,8 @@ stages:
 
 build:
     stage: build
+    before_script:
+    - apk add py3-pygments
     script:
     - cd spec
     - lualatex -shell-escape -recorder '\def\nocomments{}\input{doc.tex}'