diff --git a/.github/workflows/static_analysis.yml b/.github/workflows/static_analysis.yml
index 60fd5c0..878ab43 100644
--- a/.github/workflows/static_analysis.yml
+++ b/.github/workflows/static_analysis.yml
@@ -31,6 +31,9 @@ jobs:
       - name: Check formatting
         run: uvx ruff format --check .
 
+      - name: Check statement order
+        run: uvx ssort --check --diff .
+
   pyright:
     runs-on: ubuntu-latest
     steps:
diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index 211ae9c..2effd49 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -4,6 +4,7 @@ repos:
     rev: v6.0.0
     hooks:
       - id: check-yaml
+      - id: check-toml
       - id: end-of-file-fixer
       - id: trailing-whitespace
       - id: check-added-large-files # Prevent giant files from being committed.
@@ -11,12 +12,16 @@ repos:
         exclude: ^(uv\.lock|docs/package-lock\.json)$ # generated lock files
       - id: check-merge-conflict # Check for files that contain merge conflict strings.
   - repo: https://github.com/kynan/nbstripout
-    rev: 0.9.0
+    rev: 0.9.1
     hooks:
       - id: nbstripout # strip jupyter notebook output
+  - repo: https://github.com/bwhmather/ssort
+    rev: 0.17.0
+    hooks:
+      - id: ssort # order statements so names are defined before they are used
   - repo: https://github.com/astral-sh/ruff-pre-commit
-    rev: v0.9.1
+    rev: v0.17.3
     hooks:
-      - id: ruff
+      - id: ruff-check # lint, including import sorting (the I rules)
         args: [--fix]
       - id: ruff-format
diff --git a/Makefile b/Makefile
index ece9999..acbf9bd 100644
--- a/Makefile
+++ b/Makefile
@@ -17,9 +17,10 @@ install:  ## uv sync with the dev extra, and the pre-commit hooks
 test:  ## pytest with coverage
 	uv run pytest --cov .
 
-lint:  ## ruff and pyright
+lint:  ## ruff, ssort and pyright
 	uv run ruff check .
 	uv run ruff format --check .
+	uvx ssort --check --diff .
 	uv run pyright src/
 
 readme:  ## render README.md from README.qmd with quarto
diff --git a/scripts/check_pypi_dependencies.py b/scripts/check_pypi_dependencies.py
index 1825bb7..5dcc01a 100644
--- a/scripts/check_pypi_dependencies.py
+++ b/scripts/check_pypi_dependencies.py
@@ -91,6 +91,13 @@ def is_installable(releases: Releases, requirement: Requirement) -> bool:
     return False
 
 
+def _version_key(text: str) -> Version:
+    try:
+        return Version(text)
+    except InvalidVersion:
+        return Version("0")
+
+
 def check(pyproject: dict, fetch: Fetch = fetch_releases) -> list[str]:
     """Return one message per dependency that PyPI would reject or that cannot be installed."""
     project = pyproject.get("project", {})
@@ -139,13 +146,6 @@ def check(pyproject: dict, fetch: Fetch = fetch_releases) -> list[str]:
     return problems
 
 
-def _version_key(text: str) -> Version:
-    try:
-        return Version(text)
-    except InvalidVersion:
-        return Version("0")
-
-
 def main(argv: list[str] | None = None) -> int:
     """Run the check on a pyproject.toml; return the exit status."""
     parser = argparse.ArgumentParser(description=__doc__.split("\n\n")[0])