diff --git a/.github/workflows/mutation.yml b/.github/workflows/mutation.yml
new file mode 100644
index 0000000..9c6f1ec
--- /dev/null
+++ b/.github/workflows/mutation.yml
@@ -0,0 +1,26 @@
+on:
+  pull_request:
+    paths-ignore:
+      - 'docs/**'
+      - 'README.md'
+      - 'CHANGELOG.md'
+      - '.gitignore'
+      - '.gitattributes'
+
+  push:
+    paths-ignore:
+      - 'docs/**'
+      - 'README.md'
+      - 'CHANGELOG.md'
+      - '.gitignore'
+      - '.gitattributes'
+
+name: mutation test
+
+jobs:
+  mutation:
+    uses: php-forge/actions/.github/workflows/infection.yml@main
+    with:
+      phpstan: true
+    secrets:
+      STRYKER_DASHBOARD_API_KEY: ${{ secrets.STRYKER_DASHBOARD_API_KEY }}
diff --git a/composer.json b/composer.json
index 826163d..35d3f24 100644
--- a/composer.json
+++ b/composer.json
@@ -15,6 +15,7 @@
     },
     "require-dev": {
         "ext-simplexml": "*",
+        "infection/infection": "^0.27|^0.29",
         "maglnet/composer-require-checker": "^4.1",
         "phpstan/extension-installer": "^1.4",
         "phpstan/phpstan-strict-rules": "^2.0.3",
@@ -41,6 +42,7 @@
     "config": {
         "sort-packages": true,
         "allow-plugins": {
+            "infection/extension-installer": true,
             "phpstan/extension-installer": true,
             "yiisoft/yii2-composer": true
         }
@@ -48,6 +50,7 @@
     "scripts": {
         "check-dependencies": "./vendor/bin/composer-require-checker check",
         "ecs": "./vendor/bin/ecs --fix",
+        "mutation": "./vendor/bin/infection --threads=4 --ignore-msi-with-no-mutations --only-covered --min-msi=100 --min-covered-msi=100",
         "rector": "./vendor/bin/rector process src",
         "static": "./vendor/bin/phpstan --memory-limit=512M",
         "tests": "./vendor/bin/phpunit"
diff --git a/infection.json.dist b/infection.json5
similarity index 62%
rename from infection.json.dist
rename to infection.json5
index d06b334..15361d9 100644
--- a/infection.json.dist
+++ b/infection.json5
@@ -1,16 +1,17 @@
 {
-    "source": {
-        "directories": [
-            "src"
-        ]
-    },
+    "$schema": "vendor/infection/infection/resources/schema.json",
     "logs": {
         "text": "php:\/\/stderr",
         "stryker": {
             "report": "main"
         }
     },
-    "mutators": {
-        "@default": true
-    }
+    "source": {
+        "directories": [
+            "src"
+        ]
+    },
+    "phpStan": {
+        "configDir": "."
+    },
 }
diff --git a/phpunit.xml.dist b/phpunit.xml.dist
index 3ddadb0..2215bca 100644
--- a/phpunit.xml.dist
+++ b/phpunit.xml.dist
@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <phpunit
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-    xsi:noNamespaceSchemaLocation="https://schema.phpunit.de/10.2/phpunit.xsd"
+    xsi:noNamespaceSchemaLocation="vendor/phpunit/phpunit/phpunit.xsd"
     bootstrap="tests/bootstrap.php"
     cacheDirectory="runtime/.phpunit.cache"
     colors="true"
diff --git a/src/NestedSetsBehavior.php b/src/NestedSetsBehavior.php
index 5f12921..b7e670d 100644
--- a/src/NestedSetsBehavior.php
+++ b/src/NestedSetsBehavior.php
@@ -1199,7 +1199,7 @@ protected function moveNode(ActiveRecord $node, int $value, int $depth): void
 
             $this->shiftLeftRightAttribute($value, $delta);
 
-            if ($leftValue >= $value) {
+            if ($leftValue > $value) {
                 $leftValue += $delta;
                 $rightValue += $delta;
             }