diff --git a/config/set/downgrade-php82.php b/config/set/downgrade-php82.php
index 707b6493..372883ad 100644
--- a/config/set/downgrade-php82.php
+++ b/config/set/downgrade-php82.php
@@ -5,8 +5,12 @@
 use Rector\Config\RectorConfig;
 use Rector\Core\ValueObject\PhpVersion;
 use Rector\DowngradePhp82\Rector\Class_\DowngradeReadonlyClassRector;
+use Rector\DowngradePhp82\Rector\FunctionLike\DowngradeStandaloneNullTrueFalseReturnTypeRector;
 
 return static function (RectorConfig $rectorConfig): void {
     $rectorConfig->phpVersion(PhpVersion::PHP_81);
-    $rectorConfig->rule(DowngradeReadonlyClassRector::class);
+    $rectorConfig->rules([
+        DowngradeReadonlyClassRector::class,
+        DowngradeStandaloneNullTrueFalseReturnTypeRector::class
+    ]);
 };
diff --git a/rules/DowngradePhp82/Rector/FunctionLike/DowngradeStandaloneNullTrueFalseReturnTypeRector.php b/rules/DowngradePhp82/Rector/FunctionLike/DowngradeStandaloneNullTrueFalseReturnTypeRector.php
index c096c609..946dc830 100644
--- a/rules/DowngradePhp82/Rector/FunctionLike/DowngradeStandaloneNullTrueFalseReturnTypeRector.php
+++ b/rules/DowngradePhp82/Rector/FunctionLike/DowngradeStandaloneNullTrueFalseReturnTypeRector.php
@@ -11,7 +11,9 @@
 use PhpParser\Node\Identifier;
 use PhpParser\Node\Stmt\ClassMethod;
 use PhpParser\Node\Stmt\Function_;
+use PHPStan\Type\Constant\ConstantBooleanType;
 use PHPStan\Type\NullType;
+use PHPStan\Type\Type;
 use Rector\BetterPhpDocParser\PhpDocInfo\PhpDocInfoFactory;
 use Rector\BetterPhpDocParser\PhpDocManipulator\PhpDocTypeChanger;
 use Rector\Core\Rector\AbstractRector;
@@ -85,22 +87,36 @@ public function refactor(Node $node): ?Node
         }
 
         if (! $node instanceof ClassMethod) {
-            $node->returnType = new Identifier('mixed');
-
             // in closure and arrow function can't add `@return null` docblock as they are Expr
             // that rely on Stmt
             $phpDocInfo = $this->phpDocInfoFactory->createFromNodeOrEmpty($node);
-            $this->phpDocTypeChanger->changeReturnType($node, $phpDocInfo, new NullType());
+            $this->phpDocTypeChanger->changeReturnType($node, $phpDocInfo, $this->resolveType($node->returnType));
 
+            $node->returnType = new Identifier('mixed');
             return $node;
         }
 
+        $phpDocInfo = $this->phpDocInfoFactory->createFromNodeOrEmpty($node);
+        $this->phpDocTypeChanger->changeReturnType($node, $phpDocInfo, $this->resolveType($node->returnType));
+
         // todo: verify parent
         $node->returnType = new Identifier('mixed');
 
-        $phpDocInfo = $this->phpDocInfoFactory->createFromNodeOrEmpty($node);
-        $this->phpDocTypeChanger->changeReturnType($node, $phpDocInfo, new NullType());
-
         return $node;
     }
+
+    private function resolveType(Node $node): Type
+    {
+        $nodeName = $this->getName($node);
+
+        if ($nodeName === 'null') {
+            return new NullType();
+        }
+
+        if ($nodeName === 'false') {
+            return new ConstantBooleanType(false);
+        }
+
+        return new ConstantBooleanType(true);
+    }
 }