diff --git a/src/PhpGenerator/Dumper.php b/src/PhpGenerator/Dumper.php
index 24e929df..84d90a2d 100644
--- a/src/PhpGenerator/Dumper.php
+++ b/src/PhpGenerator/Dumper.php
@@ -22,6 +22,7 @@ final class Dumper
 	public int $maxDepth = 50;
 	public int $wrapLength = 120;
 	public string $indentation = "\t";
+	public bool $customObjects = true;
 
 
 	/**
@@ -169,8 +170,11 @@ private function dumpObject(object $var, array $parents, int $level, int $column
 
 			throw new Nette\InvalidStateException('Cannot dump object of type Closure.');
 
-		} else {
+		} elseif ($this->customObjects) {
 			return $this->dumpCustomObject($var, $parents, $level);
+
+		} else {
+			throw new Nette\InvalidStateException("Cannot dump object of type $class.");
 		}
 	}
 
diff --git a/tests/PhpGenerator/Dumper.dump().phpt b/tests/PhpGenerator/Dumper.dump().phpt
index f9e1d507..8dae1852 100644
--- a/tests/PhpGenerator/Dumper.dump().phpt
+++ b/tests/PhpGenerator/Dumper.dump().phpt
@@ -198,3 +198,13 @@ same(
 		XX,
 	$dumper->dump(new TestDateTime('2016-06-22 20:52:43.1234', new DateTimeZone('Europe/Prague'))),
 );
+
+
+// disallow custom objects
+$dumper = new Dumper;
+$dumper->customObjects = false;
+Assert::exception(
+	fn() => $dumper->dump(new TestSer),
+	Nette\InvalidStateException::class,
+	'Cannot dump object of type TestSer.',
+);