diff --git a/src/TypeValidator.php b/src/TypeValidator.php
index d8b0046..84281c7 100644
--- a/src/TypeValidator.php
+++ b/src/TypeValidator.php
@@ -52,7 +52,7 @@ public function validate($value): void
         $actualType = gettype($value);
 
         foreach ($this->allowedTypes as $type) {
-            if ($actualType === $type) {
+            if (strtolower($actualType) === strtolower($type)) {
                 return;
             }
 
diff --git a/tests/Fixtures/SampleData.php b/tests/Fixtures/SampleData.php
index 4c0667c..0a9e84c 100644
--- a/tests/Fixtures/SampleData.php
+++ b/tests/Fixtures/SampleData.php
@@ -20,5 +20,11 @@ class SampleData extends DataTransferObject
     /** @var Foo|string */
     public string $union_prop;
 
+    /** @var string|null */
+    public $nullable_doctype_prop;
+
+    /** @var Boolean|Int|String */
+    public $mixed_case_type_prop;
+
     public NestedData $nested;
 }
diff --git a/tests/Unit/DataTransferObjectTest.php b/tests/Unit/DataTransferObjectTest.php
index da45929..01fcc6f 100644
--- a/tests/Unit/DataTransferObjectTest.php
+++ b/tests/Unit/DataTransferObjectTest.php
@@ -97,6 +97,31 @@ public function testUnionProperty($value): void
         self::assertEquals(['union_prop' => $value], $data->toArray());
     }
 
+    public function testNullableTypeViaDocBlockProperty(): void
+    {
+        $data = SampleData::make(['nullable_doctype_prop' => null]);
+
+        self::assertEquals(['nullable_doctype_prop' => null], $data->toArray());
+    }
+
+    /** @return array<mixed> */
+    public function provideMixedCaseTypeValues(): array
+    {
+        return [
+            [false],
+            [100],
+            ['foo'],
+        ];
+    }
+
+    /** @dataProvider provideMixedCaseTypeValues */
+    public function testMixedCaseTypeDocBlockProperty($value): void
+    {
+        $data = SampleData::make(['mixed_case_type_prop' => $value]);
+
+        self::assertEquals(['mixed_case_type_prop' => $value], $data->toArray());
+    }
+
     public function testNativeNullablePropertyAcceptsNull(): void
     {
         $data = SampleData::make();