diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 991d22ed..4a31e0e5 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -178,6 +178,17 @@ jobs:
       - name: "Install dependencies"
         run: "composer install --no-interaction --no-progress"
 
+      - name: "Checkout build-infection"
+        uses: actions/checkout@v5
+        with:
+          repository: "phpstan/build-infection"
+          path: "build-infection"
+          ref: "1.x"
+
+      - name: "Install build-infection dependencies"
+        working-directory: "build-infection"
+        run: "composer install --no-interaction --no-progress"
+
       - uses: "actions/download-artifact@v4"
         with:
           name: "result-cache-${{ matrix.php-version }}"
diff --git a/infection.json5 b/infection.json5
index 7afd7230..f6a55ac1 100644
--- a/infection.json5
+++ b/infection.json5
@@ -10,6 +10,7 @@
   "logs": {
     "text": "tmp/infection.log"
   },
+  "bootstrap": "build-infection/vendor/autoload.php",
   "mutators": {
     "@default": false,
     "PHPStan\\Infection\\TrinaryLogicMutator": true
diff --git a/phpstan.neon b/phpstan.neon
index 385b9690..b5f35ecc 100644
--- a/phpstan.neon
+++ b/phpstan.neon
@@ -25,7 +25,6 @@ parameters:
 		- tests/*/data-attributes/*
 		- tests/*/data-php-*/*
 		- tests/Rules/Doctrine/ORM/entity-manager.php
-		- tests/Infection/
 
 	reportUnmatchedIgnoredErrors: false
 
diff --git a/tests/Infection/TrinaryLogicMutator.php b/tests/Infection/TrinaryLogicMutator.php
deleted file mode 100644
index 67e9b530..00000000
--- a/tests/Infection/TrinaryLogicMutator.php
+++ /dev/null
@@ -1,69 +0,0 @@
-<?php declare(strict_types = 1);
-
-namespace PHPStan\Infection;
-
-use Infection\Mutator\Definition;
-use Infection\Mutator\Mutator;
-use Infection\Mutator\MutatorCategory;
-use LogicException;
-use PhpParser\Node;
-use function in_array;
-
-/**
- * @implements Mutator<Node\Expr\MethodCall>
- */
-final class TrinaryLogicMutator implements Mutator
-{
-
-	public static function getDefinition(): Definition
-	{
-		return new Definition(
-			<<<'TXT'
-				Replaces TrinaryLogic->yes() with !TrinaryLogic->no() and vice versa.
-				TXT
-			,
-			MutatorCategory::ORTHOGONAL_REPLACEMENT,
-			null,
-			<<<'DIFF'
-				- $type->isBoolean()->yes();
-				+ !$type->isBoolean()->no();
-			DIFF,
-		);
-	}
-
-	public function getName(): string
-	{
-		return 'TrinaryLogicMutator';
-	}
-
-	public function canMutate(Node $node): bool
-	{
-		if (!$node instanceof Node\Expr\MethodCall) {
-			return false;
-		}
-
-		if (!$node->name instanceof Node\Identifier) {
-			return false;
-		}
-
-		if (!in_array($node->name->name, ['yes', 'no'], true)) {
-			return false;
-		}
-
-		return true;
-	}
-
-	public function mutate(Node $node): iterable
-	{
-		if (!$node->name instanceof Node\Identifier) {
-			throw new LogicException();
-		}
-
-		if ($node->name->name === 'yes') {
-			yield new Node\Expr\BooleanNot(new Node\Expr\MethodCall($node->var, 'no'));
-		} else {
-			yield new Node\Expr\BooleanNot(new Node\Expr\MethodCall($node->var, 'yes'));
-		}
-	}
-
-}