diff --git a/src/Php/CompilerBase.php b/src/Php/CompilerBase.php
index cc3c77c6..fe4b1edf 100644
--- a/src/Php/CompilerBase.php
+++ b/src/Php/CompilerBase.php
@@ -2851,7 +2851,13 @@ class CompilerBase extends \PhpAot\Core\Translator
 
     protected function parseInstanceof(Node\Expr\Instanceof_ $expr): string
     {
-        return $this->convertToObject($expr->expr) . '.instanceOf(' . $this->identifierToStr($expr->class) . ')';
+        if ($this->isNameExpr($expr->class)) {
+            $className = $this->getNamespacedClassName($this->parseIdentifier($expr->class));
+            $className = $this->getClassEntryPtr($className);
+            return 'php::instanceOf(' . $this->parseExpr($expr->expr) . ', ' . $className . ')';
+        } else {
+            return 'php::instanceOf(' . $this->parseExpr($expr->expr) . ', ' . $this->identifierToStr($expr->class) . ')';
+        }
     }
 
     protected function parseCastInt(Node\Expr\Cast\Int_ $node): string
diff --git a/tests/aot/union-intersection-types.phpt b/tests/aot/union-intersection-types.phpt
new file mode 100644
index 00000000..0201356e
--- /dev/null
+++ b/tests/aot/union-intersection-types.phpt
@@ -0,0 +1,113 @@
+--TEST--
+Union Types and Intersection Types - PHP 8+ type system
+--SKIPIF--
+--FILE--
+<?php
+// Test union types
+class Shape {
+    public function getName(): string {
+        return "Shape";
+    }
+}
+
+class Circle extends Shape {
+    private float $radius;
+    
+    public function __construct(float $radius) {
+        $this->radius = $radius;
+    }
+    
+    public function getArea(): float {
+        return M_PI * $this->radius * $this->radius;
+    }
+}
+
+class Square extends Shape {
+    private float $side;
+    
+    public function __construct(float $side) {
+        $this->side = $side;
+    }
+    
+    public function getArea(): float {
+        return $this->side * $this->side;
+    }
+}
+
+function process_shape(Shape|float $shape): float|string {
+    if ($shape instanceof Shape) {
+        return $shape->getArea();
+    } else {
+        return "Invalid shape: " . $shape;
+    }
+}
+
+// Test nullable union types
+function format_value(int|string|null $value): string {
+    if ($value === null) {
+        return "No value";
+    }
+    return "Value: " . $value;
+}
+
+// Test mixed type (PHP 8.0+)
+function handle_mixed(mixed $data): mixed {
+    return $data;
+}
+
+// Test never type (PHP 8.0+)
+function redirect(string $url): never {
+    throw new \RuntimeException("Redirecting to: " . $url);
+}
+
+function main() {
+    // Test union types with instanceof
+    $circle = new Circle(5.0);
+    var_dump(process_shape($circle));
+    
+    $square = new Square(4.0);
+    var_dump(process_shape($square));
+    
+    var_dump(process_shape(100.5));
+    
+    // Test nullable union
+    var_dump(format_value(42));
+    var_dump(format_value("hello"));
+    var_dump(format_value(null));
+    
+    // Test mixed type
+    var_dump(handle_mixed(42));
+    var_dump(handle_mixed("string"));
+    var_dump(handle_mixed([1, 2, 3]));
+    var_dump(handle_mixed(new Circle(1.0)));
+    
+    // Test never type (will throw exception)
+    try {
+        redirect("http://example.com");
+    } catch (RuntimeException $e) {
+        var_dump($e->getMessage());
+    }
+}
+?>
+--EXPECT--
+float(78.53981633974483)
+float(16)
+string(20) "Invalid shape: 100.5"
+string(9) "Value: 42"
+string(12) "Value: hello"
+string(8) "No value"
+int(42)
+string(6) "string"
+array(3) {
+  [0]=>
+  int(1)
+  [1]=>
+  int(2)
+  [2]=>
+  int(3)
+}
+object(Circle)#3 (1) {
+  ["radius":"Circle":private]=>
+  float(1)
+}
+string(34) "Redirecting to: http://example.com"