diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 555e2fd3..46463e6b 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -479,9 +479,11 @@ servergitmirrors:
     - diff repo/index-v1.jar index-v1.jar
 
 Build documentation:
-  image: python:3.9-buster
+  image: debian:bullseye
+  <<: *apt-template
   script:
-    - pip install -e .[docs]
+    - apt-get install python3-pip make
+    - pip install .[docs]
     - pydocstyle fdroidserver
     - cd docs
     - sphinx-apidoc -o ./source ../fdroidserver -M -e
diff --git a/pyproject.toml b/pyproject.toml
index ba6a2e12..558596e9 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,10 +1,10 @@
 [tool.black]
 skip-string-normalization = true
-target-version = ["py35"]
+target-version = ["py39"]
 
 
 [tool.mypy]
-python_version = "3.5"
+python_version = "3.9"
 
 files = "fdroidserver"
 
diff --git a/setup.py b/setup.py
index 253637ec..741b6877 100755
--- a/setup.py
+++ b/setup.py
@@ -94,7 +94,7 @@ setup(
     scripts=['makebuildserver'],
     entry_points={'console_scripts': ['fdroid=fdroidserver.__main__:main']},
     data_files=get_data_files(),
-    python_requires='>=3.5',
+    python_requires='>=3.9',
     cmdclass={
         'versioncheck': VersionCheckCommand,
         'install': InstallWithCompile,