diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 531bc1c..f19618c 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -75,6 +75,10 @@ jobs:
         options: --health-cmd="mysqladmin ping" --health-interval=10s --health-timeout=5s --health-retries=5
     steps:
       - uses: actions/checkout@v4
+      - name: Install subversion
+        # ubuntu-latest no longer ships svn preinstalled. The WP test suite
+        # bootstrap script checks out develop.svn.wordpress.org via svn.
+        run: sudo apt-get update -qq && sudo apt-get install -y --no-install-recommends subversion
       - name: Setup PHP ${{ matrix.php }}
         uses: shivammathur/setup-php@v2
         with: