diff --git a/composer.json b/composer.json
index 45329ab1..17e28b7c 100644
--- a/composer.json
+++ b/composer.json
@@ -28,7 +28,7 @@
   "require-dev": {
     "phpunit/phpunit": "^9.0",
     "symfony/yaml": "^5.0|^6.0|^7.0",
-    "vimeo/psalm": "^5.0"
+    "vimeo/psalm": "^5.0|^6.0"
   },
   "autoload": {
     "psr-4": {
diff --git a/psalm.xml b/psalm.xml
index 3e4e3d08..415e0fe3 100644
--- a/psalm.xml
+++ b/psalm.xml
@@ -12,4 +12,11 @@
             <directory name="vendor" />
         </ignoreFiles>
     </projectFiles>
+    <issueHandlers>
+        <UnusedClass errorLevel="suppress" />
+        <PossiblyUnusedMethod errorLevel="suppress" />
+        <UnusedForeachValue errorLevel="suppress" />
+        <PossiblyUnusedReturnValue errorLevel="suppress" />
+        <UnusedVariable errorLevel="suppress" />
+    </issueHandlers>
 </psalm>
diff --git a/src/Generator/MarkupAbstract.php b/src/Generator/MarkupAbstract.php
index deecc5fa..31027a07 100644
--- a/src/Generator/MarkupAbstract.php
+++ b/src/Generator/MarkupAbstract.php
@@ -30,7 +30,6 @@
 abstract class MarkupAbstract extends CodeGeneratorAbstract
 {
     protected int $heading;
-    protected string $prefix;
 
     public function __construct(?Config $config = null)
     {
@@ -39,6 +38,5 @@ public function __construct(?Config $config = null)
         $heading = (int) $config?->get('heading');
 
         $this->heading = $heading >= 1 && $heading <= 6 ? $heading : 1;
-        $this->prefix  = $config?->get('prefix') ?? 'psx_model_';
     }
 }
diff --git a/src/Generator/Normalizer/NormalizerAbstract.php b/src/Generator/Normalizer/NormalizerAbstract.php
index 09e0f982..d13d8302 100644
--- a/src/Generator/Normalizer/NormalizerAbstract.php
+++ b/src/Generator/Normalizer/NormalizerAbstract.php
@@ -168,7 +168,7 @@ protected function sanitizeName(string $name): string
             return $name;
         }
 
-        return preg_replace('/[^a-zA-Z_]/', '_', $name);
+        return (string) preg_replace('/[^a-zA-Z_]/', '_', $name);
     }
 
     private function case(string $name, int $style): string
diff --git a/src/Generator/Php.php b/src/Generator/Php.php
index 324c91b5..892b14a1 100644
--- a/src/Generator/Php.php
+++ b/src/Generator/Php.php
@@ -383,7 +383,7 @@ private function prettyPrint($class, array $uses): string
         }
     }
 
-    private function buildToRecord(\PhpParser\Builder\Class_ $class, array $properties, bool $hasParent): void
+    private function buildToRecord(Class_ $class, array $properties, bool $hasParent): void
     {
         $stmts = [];
         if ($hasParent) {
@@ -400,10 +400,10 @@ private function buildToRecord(\PhpParser\Builder\Class_ $class, array $properti
 
         foreach ($properties as $name => $property) {
             /** @var Code\Property $property */
-            $stmts[] = new Node\Expr\MethodCall(new Node\Expr\Variable('record'), new Node\Identifier('put'), [
+            $stmts[] = new Node\Stmt\Expression(new Node\Expr\MethodCall(new Node\Expr\Variable('record'), new Node\Identifier('put'), [
                 new Node\Arg(new Node\Scalar\String_($property->getName()->getRaw())),
                 new Node\Arg(new Node\Expr\PropertyFetch(new Node\Expr\Variable('this'), $name)),
-            ]);
+            ]));
         }
 
         $stmts[] = new Node\Stmt\Return_(new Node\Expr\Variable('record'));
diff --git a/src/Generator/Swift.php b/src/Generator/Swift.php
index 7f0177a4..e302a427 100644
--- a/src/Generator/Swift.php
+++ b/src/Generator/Swift.php
@@ -78,7 +78,6 @@ protected function writeStruct(Code\Name $name, array $properties, ?string $exte
             /** @var Code\Property $property */
             $keys[$property->getName()->getProperty()] = $property->getName()->getRaw();
 
-            /** @var Code\Property $property */
             $code.= $this->indent . 'var ' . $property->getName()->getProperty() . ': ' . $property->getType() . "\n";
         }
 
diff --git a/src/Inspector/ChangelogGenerator.php b/src/Inspector/ChangelogGenerator.php
index 3c8d2203..a284ef8e 100644
--- a/src/Inspector/ChangelogGenerator.php
+++ b/src/Inspector/ChangelogGenerator.php
@@ -69,7 +69,7 @@ public function generateDefinitionType(DefinitionTypeAbstract $leftType, Definit
         yield from $this->generateDefinition($leftType, $rightType, $typeName, $propertyName);
 
         if ($leftType instanceof StructDefinitionType && $rightType instanceof StructDefinitionType) {
-            yield from $this->generateStruct($leftType, $rightType, $typeName, $propertyName);
+            yield from $this->generateStruct($leftType, $rightType, $typeName);
         } elseif ($leftType instanceof MapDefinitionType && $rightType instanceof MapDefinitionType) {
             yield from $this->generateMap($leftType, $rightType, $typeName, $propertyName);
         } elseif ($leftType instanceof ArrayDefinitionType && $rightType instanceof ArrayDefinitionType) {
@@ -88,7 +88,7 @@ private function generateDefinition(DefinitionTypeAbstract $leftType, Definition
         }
     }
 
-    private function generateStruct(StructDefinitionType $leftType, StructDefinitionType $rightType, string $typeName, ?string $propertyName = null): \Generator
+    private function generateStruct(StructDefinitionType $leftType, StructDefinitionType $rightType, string $typeName): \Generator
     {
         $left = $leftType->getProperties() ?? [];
         $right = $rightType->getProperties() ?? [];
diff --git a/src/Parser/Documentor.php b/src/Parser/Documentor.php
index 254e4ae2..604b65f0 100644
--- a/src/Parser/Documentor.php
+++ b/src/Parser/Documentor.php
@@ -43,7 +43,6 @@
  */
 class Documentor extends Popo
 {
-    private ContextFactory $contextFactory;
     private TypeResolver $typeResolver;
     private Popo\Resolver\Documentor $documentor;
 
@@ -51,7 +50,6 @@ public function __construct()
     {
         parent::__construct();
 
-        $this->contextFactory = new ContextFactory();
         $this->typeResolver = new TypeResolver();
         $this->documentor = new Popo\Resolver\Documentor();
     }