diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 97c4d9981..aee121da7 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -35,10 +35,14 @@ jobs:
             php: "8.1"
             coverage: "pcov"
           # Only test pre-installed (i.e. fast) versions of PHP on Windows.
-          - os: "windows-2022"
+          - os: "windows-2019"
             php: "8.2"
             coverage: "none"
     steps:
+      - name: Disable Windows Defender
+        if: matrix.os == 'windows-2019'
+        run: Set-MpPreference -DisableRealtimeMonitoring $true
+        shell: powershell
       - name: Prepare Git
         # Windows corrupts line endings on checkout, causing test failures.
         run: git config --global core.autocrlf false