diff --git a/changelog.d/587-format.md b/changelog.d/587-format.md
new file mode 100644
index 000000000..7016708d9
--- /dev/null
+++ b/changelog.d/587-format.md
@@ -0,0 +1 @@
+- Apply ruff formatting to the validation notebook (blank line after the warnings import) so the repo-wide `ruff format --check` lint passes on main.
diff --git a/docs/book/validation/validation.ipynb b/docs/book/validation/validation.ipynb
index b937c1c72..ca15f9534 100644
--- a/docs/book/validation/validation.ipynb
+++ b/docs/book/validation/validation.ipynb
@@ -1790,6 +1790,7 @@
    ],
    "source": [
     "import warnings\n",
+    "\n",
     "warnings.filterwarnings(\"ignore\")\n",
     "\n",
     "from policyengine_uk import Microsimulation\n",