diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 2e87e97..8562ad8 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -5,12 +5,13 @@ variables:
 
 cache:
   paths:
-    - "$CI_PROJECT_DIR/pip-cache"
+    - "$PIP_CACHE_DIR"
   key: "$CI_PROJECT_ID"
 
 .install_sphinx:
   before_script:
-  - pip install -U -r docs/requirements.txt
+  - apk add gcc musl-dev
+  - pip install --cache-dir "$PIP_CACHE_DIR" -U -r docs/requirements.txt
 
 test-docs:
   stage: test
diff --git a/docs/requirements.txt b/docs/requirements.txt
index f828e1c..2fc0c18 100644
--- a/docs/requirements.txt
+++ b/docs/requirements.txt
@@ -1,5 +1,4 @@
 reno[sphinx]==3.5.0
-dulwich --global-option='--pure'
 Sphinx==5.1.1
 sphinx-theme-pd==0.8.3