diff --git a/.gitpod.yml b/.gitpod.yml
index 9d8eb2b..f060745 100644
--- a/.gitpod.yml
+++ b/.gitpod.yml
@@ -1,5 +1,5 @@
 tasks:
-  - init: pyenv local 3.8
+  - init: pyenv local 3.9
   - init: pip install -e .[dev]
 
 github:
diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index 8eb7a7c..1f4390e 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -37,8 +37,25 @@ repos:
     hooks:
       - id: black
 
+  - repo: https://github.com/pre-commit/mirrors-prettier
+    rev: v4.0.0-alpha.8
+    hooks:
+      - id: prettier
+
+  - repo: https://github.com/ComPWA/mirrors-taplo
+    rev: v0.8.1
+    hooks:
+      - id: taplo
+
+  - repo: https://github.com/pappasam/toml-sort
+    rev: v0.23.1
+    hooks:
+      - id: toml-sort
+        args: [--in-place]
+        exclude: (?x)^(labels.*\.toml)$
+
   - repo: https://github.com/ComPWA/policy
-    rev: 0.2.0
+    rev: 0.2.3
     hooks:
       - id: check-dev-files
         args:
@@ -66,11 +83,6 @@ repos:
             .*\.py
           )$
 
-  - repo: https://github.com/pre-commit/mirrors-prettier
-    rev: v4.0.0-alpha.8
-    hooks:
-      - id: prettier
-
   - repo: https://github.com/ComPWA/mirrors-pyright
     rev: v1.1.345
     hooks:
@@ -82,16 +94,3 @@ repos:
       - id: ruff
         args:
           - --fix
-
-  - repo: https://github.com/ComPWA/mirrors-taplo
-    rev: v0.8.1
-    hooks:
-      - id: taplo
-
-  - repo: https://github.com/pappasam/toml-sort
-    rev: v0.23.1
-    hooks:
-      - id: toml-sort
-        args:
-          - --in-place
-        exclude: (?x)^(labels.*\.toml)$
diff --git a/.readthedocs.yml b/.readthedocs.yml
index 480b609..5ccfea1 100644
--- a/.readthedocs.yml
+++ b/.readthedocs.yml
@@ -11,7 +11,7 @@ formats:
 build:
   os: ubuntu-22.04
   tools:
-    python: "3.8"
+    python: "3.9"
   jobs:
     post_install:
       - pip install -e .[doc]
diff --git a/environment.yml b/environment.yml
index a4e0365..768e973 100644
--- a/environment.yml
+++ b/environment.yml
@@ -2,7 +2,7 @@ name: bossdoc
 channels:
   - defaults
 dependencies:
-  - python==3.8.*
+  - python==3.9.*
   - pip
   - pip:
       - -e .[dev]