diff --git a/build/target-repository/composer.json b/build/target-repository/composer.json
index 6b5f8e0a30d..68290e50bba 100644
--- a/build/target-repository/composer.json
+++ b/build/target-repository/composer.json
@@ -9,7 +9,7 @@
     ],
     "require": {
         "php": "^7.4|^8.0",
-        "phpstan/phpstan": "^2.1.40"
+        "phpstan/phpstan": "^2.1.41"
     },
     "autoload": {
         "files": [
diff --git a/composer.json b/composer.json
index 48122114326..e7172771349 100644
--- a/composer.json
+++ b/composer.json
@@ -23,7 +23,7 @@
         "nikic/php-parser": "^5.7",
         "ondram/ci-detector": "^4.2",
         "phpstan/phpdoc-parser": "^2.3",
-        "phpstan/phpstan": "^2.1.40",
+        "phpstan/phpstan": "^2.1.41",
         "react/event-loop": "^1.6",
         "react/promise": "^3.3",
         "react/socket": "^1.17",
diff --git a/rules/DeadCode/Rector/FunctionLike/NarrowWideUnionReturnTypeRector.php b/rules/DeadCode/Rector/FunctionLike/NarrowWideUnionReturnTypeRector.php
index b90cc345753..2ecc8ddd341 100644
--- a/rules/DeadCode/Rector/FunctionLike/NarrowWideUnionReturnTypeRector.php
+++ b/rules/DeadCode/Rector/FunctionLike/NarrowWideUnionReturnTypeRector.php
@@ -35,7 +35,6 @@
 use Rector\VersionBonding\Contract\MinPhpVersionInterface;
 use Symplify\RuleDocGenerator\ValueObject\CodeSample\CodeSample;
 use Symplify\RuleDocGenerator\ValueObject\RuleDefinition;
-use Webmozart\Assert\Assert;
 
 /**
  * @see \Rector\Tests\DeadCode\Rector\FunctionLike\NarrowWideUnionReturnTypeRector\NarrowWideUnionReturnTypeRectorTest
@@ -126,10 +125,11 @@ public function refactor(Node $node): ?Node
         $hasImplicitNullReturn = $this->silentVoidResolver->hasSilentVoid($node)
             || $this->hasImplicitNullReturn($returnStatements);
 
+        /** @var UnionType|NullableType $returnType */
         $returnType = $node->returnType;
-        Assert::isInstanceOfAny($returnType, [UnionType::class, NullableType::class]);
 
         $returnType = $this->staticTypeMapper->mapPhpParserNodePHPStanType($returnType);
+
         $actualReturnTypes = $this->collectActualReturnTypes($returnStatements);
 
         if ($hasImplicitNullReturn) {