diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index c6287f2377973f410e8b9d7b27a8783b62c08e42..cc73eb5aa194cd103f05eec01bb131f42acd678c 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -276,20 +276,9 @@ typecheck:
 
 # -------------------- Unit Tests ---------------------------------------------------------------------
 
-# Normal test - runs on every commit all but "long run" tests
-tests-and-coverage:
+.testsuite-base:
   stage: "Unit Tests"
   needs: []
-  image: i10git.cs.fau.de:5005/pycodegen/pycodegen/nox:ubuntu24.04-cuda12.6
-  script:
-    - mkdir -p ~/.config/matplotlib
-    - echo "backend:template" > ~/.config/matplotlib/matplotlibrc
-    - mkdir public
-    - nox --session "testsuite(cupy12)"
-  tags:
-    - docker
-    - cuda11
-    - AVX
   coverage: /Total coverage:\s\d+.\d+\%/
   artifacts:
     when: always
@@ -302,6 +291,28 @@ tests-and-coverage:
         path: coverage.xml
       junit: report.xml
 
+"testsuite-gpu-py3.10":
+  extends: .testsuite-base
+  image: i10git.cs.fau.de:5005/pycodegen/pycodegen/nox:ubuntu24.04-cuda12.6
+  script:
+    - mkdir -p ~/.config/matplotlib
+    - echo "backend:template" > ~/.config/matplotlib/matplotlibrc
+    - mkdir public
+    - nox --session "testsuite-3.10(cupy12)"
+  tags:
+    - docker
+    - cuda11
+    - AVX
+
+"testsuite-cpu-py3.13":
+  extends: .testsuite-base
+  image: i10git.cs.fau.de:5005/pycodegen/pycodegen/nox:alpine
+  script:
+    - nox --session "testsuite-3.13(cpu)"
+  tags:
+    - docker
+    - AVX
+
 # -------------------- Documentation ---------------------------------------------------------------------
 
 
@@ -322,7 +333,7 @@ build-documentation:
 pages:
   image: alpine:latest
   stage: deploy
-  needs: ["tests-and-coverage", "build-documentation"]
+  needs: ["testsuite-gpu-py3.10", "build-documentation"]
   script:
     - mv docs/build/html public
     - mv coverage_report public/coverage_report
diff --git a/noxfile.py b/noxfile.py
index 1b882478ac18bfc634e117926c8a0c6b9b94fbc8..11b3731ec8100cc4fb6c20d1e45ad6f115d35ffa 100644
--- a/noxfile.py
+++ b/noxfile.py
@@ -86,8 +86,8 @@ def typecheck(session: nox.Session):
     session.run("mypy", "src/pystencils")
 
 
+@nox.session(python=["3.10", "3.12", "3.13"], tags=["test"])
 @nox.parametrize("cupy_version", [None, "12", "13"], ids=["cpu", "cupy12", "cupy13"])
-@nox.session(python="3.10", tags=["test"])
 def testsuite(session: nox.Session, cupy_version: str | None):
     if cupy_version is not None:
         install_cupy(session, cupy_version, skip_if_no_cuda=True)
diff --git a/src/pystencils/codegen/config.py b/src/pystencils/codegen/config.py
index cbb3f4f32ef82662c51facb4c2ddae0d6dba349a..d56fe66424fedc9983b227450c985ea5d931646a 100644
--- a/src/pystencils/codegen/config.py
+++ b/src/pystencils/codegen/config.py
@@ -196,12 +196,16 @@ class Category(Generic[Category_T]):
 
     def __get__(self, obj: ConfigBase, objtype: type[ConfigBase] | None = None) -> Category_T:
         if obj is None:
-            return self._default
+            return None
 
-        return cast(Category_T, getattr(obj, self._lookup, None))
+        cat = getattr(obj, self._lookup, None)
+        if cat is None:
+            cat = self._default.copy()
+            setattr(obj, self._lookup, cat)
+        return cast(Category_T, cat)
 
-    def __set__(self, obj: ConfigBase, cat: Category_T):
-        setattr(obj, self._lookup, cat.copy())
+    def __set__(self, obj: ConfigBase, cat: Category_T | None):
+        setattr(obj, self._lookup, cat.copy() if cat is not None else None)
 
 
 class _AUTO_TYPE: ...  # noqa: E701