diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 7f05981..96c66fe 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -37,9 +37,6 @@ jobs:
           - php: '8.3'
             moodle-branch: 'main'
             database: 'pgsql'
-          - php: '8.1'
-            moodle-branch: 'MOODLE_403_STABLE'
-            database: 'pgsql'
 
     steps:
       - name: checkout plugin
diff --git a/.infection.json5 b/.infection.json5
new file mode 100644
index 0000000..d0d5700
--- /dev/null
+++ b/.infection.json5
@@ -0,0 +1,17 @@
+{
+    "$schema": "https://raw.githubusercontent.com/infection/infection/0.27.0/resources/schema.json",
+    "source": {
+        "directories": [
+            ".",
+        ],
+    },
+    "mutators": {
+        "@default": true,
+    },
+    "phpUnit": {
+        "configDir": ".",
+        "customPath": "./vendor/bin/phpunit"
+    },
+    "initialTestsPhpOptions": "-dxdebug.mode=off -dpcov.enabled=1 -dpcov.directory=.",
+    "bootstrap": "./vendor/autoloadmoodle.php"
+}