diff --git a/readme.md b/readme.md
index 33ba4332..aa96e1d5 100644
--- a/readme.md
+++ b/readme.md
@@ -538,7 +538,8 @@ Each type or union/intersection type can be passed as a string, you can also use
 use Nette\PhpGenerator\Type;
 
 $member->setType('array'); // or Type::Array;
-$member->setType('array|string'); // or Type::union('array', 'string')
+$member->setType('?array'); // or Type::nullable(Type::Array);
+$member->setType('array|string'); // or Type::union(Type::Array, Type::String)
 $member->setType('Foo&Bar'); // or Type::intersection(Foo::class, Bar::class)
 $member->setType(null); // removes type
 ```
diff --git a/src/PhpGenerator/Type.php b/src/PhpGenerator/Type.php
index d122ab71..0b519e57 100644
--- a/src/PhpGenerator/Type.php
+++ b/src/PhpGenerator/Type.php
@@ -9,6 +9,8 @@
 
 namespace Nette\PhpGenerator;
 
+use Nette;
+
 
 /**
  * PHP return, property and parameter types.
@@ -85,7 +87,25 @@ class Type
 
 	public static function nullable(string $type, bool $nullable = true): string
 	{
-		return ($nullable ? '?' : '') . ltrim($type, '?');
+		if (str_contains($type, '&')) {
+			return $nullable
+				? throw new Nette\InvalidArgumentException('Intersection types cannot be nullable.')
+				: $type;
+		}
+
+		$nnType = preg_replace('#^\?|^null\||\|null(?=\||$)#i', '', $type);
+		$always = (bool) preg_match('#^(null|mixed)$#i', $nnType);
+		if ($nullable) {
+			return match (true) {
+				$always, $type !== $nnType => $type,
+				str_contains($type, '|') => $type . '|null',
+				default => '?' . $type,
+			};
+		} else {
+			return $always
+				? throw new Nette\InvalidArgumentException("Type $type cannot be not nullable.")
+				: $nnType;
+		}
 	}
 
 
diff --git a/tests/PhpGenerator/Type.phpt b/tests/PhpGenerator/Type.phpt
index aa737db6..a2f54cee 100644
--- a/tests/PhpGenerator/Type.phpt
+++ b/tests/PhpGenerator/Type.phpt
@@ -6,12 +6,50 @@ use Nette\PhpGenerator\Type;
 use Tester\Assert;
 require __DIR__ . '/../bootstrap.php';
 
+// Nullable
+Assert::same('?int', Type::nullable(Type::Int));
+Assert::same('int', Type::nullable(Type::Int, nullable: false));
 
-Assert::same('A|string', Type::union(A::class, Type::String));
+Assert::same('?int', Type::nullable('?int'));
+Assert::same('int', Type::nullable('?int', nullable: false));
+
+Assert::same('null', Type::nullable('null'));
+Assert::same('NULL', Type::nullable('NULL'));
+Assert::exception(
+	fn() => Type::nullable('null', nullable: false),
+	Nette\InvalidArgumentException::class,
+	'Type null cannot be not nullable.',
+);
+
+Assert::same('mixed', Type::nullable('mixed'));
+Assert::exception(
+	fn() => Type::nullable('mixed', nullable: false),
+	Nette\InvalidArgumentException::class,
+	'Type mixed cannot be not nullable.',
+);
+
+Assert::same('int|float|string|null', Type::nullable('int|float|string'));
+Assert::same('int|float|string', Type::nullable('int|float|string', nullable: false));
+
+Assert::same('NULL|int|float|string', Type::nullable('NULL|int|float|string'));
+Assert::same('int|float|string', Type::nullable('NULL|int|float|string', nullable: false));
 
-Assert::same('?A', Type::nullable(A::class));
-Assert::same('?A', Type::nullable(A::class));
-Assert::same('A', Type::nullable(A::class, nullable: false));
+Assert::same('int|float|string|null', Type::nullable('int|float|string|null'));
+Assert::same('int|float|string', Type::nullable('int|float|string|null', nullable: false));
+
+Assert::same('int|float|null|string', Type::nullable('int|float|null|string'));
+Assert::same('int|float|string', Type::nullable('int|float|null|string', nullable: false));
+
+Assert::exception(
+	fn() => Type::nullable('Foo&Bar'),
+	Nette\InvalidArgumentException::class,
+	'Intersection types cannot be nullable.',
+);
+Assert::same('Foo&Bar', Type::nullable('Foo&Bar', nullable: false));
+
+
+// Union
+Assert::same('A|string', Type::union(A::class, Type::String));
 
-Assert::same('?A', Type::nullable('?A'));
-Assert::same('A', Type::nullable('?A', nullable: false));
+// Intersection
+Assert::same('A&string', Type::intersection(A::class, Type::String));