diff --git a/src/Uuid.php b/src/Uuid.php
index 945480b..5f0922b 100644
--- a/src/Uuid.php
+++ b/src/Uuid.php
@@ -476,10 +476,11 @@ class Uuid implements UuidInterface
      */
     public static function fromString(string $uuid): UuidInterface
     {
+        $uuid = strtolower($uuid);
         if (! self::$factoryReplaced && preg_match(LazyUuidFromString::VALID_REGEX, $uuid) === 1) {
             assert($uuid !== '');
 
-            return new LazyUuidFromString(strtolower($uuid));
+            return new LazyUuidFromString($uuid);
         }
 
         return self::getFactory()->fromString($uuid);
diff --git a/tests/UuidTest.php b/tests/UuidTest.php
index 29f1761..2ebac1d 100644
--- a/tests/UuidTest.php
+++ b/tests/UuidTest.php
@@ -132,6 +132,17 @@ class UuidTest extends TestCase
         Uuid::fromString('');
     }
 
+    public function testFromStringUppercase(): void
+    {
+        $uuid = Uuid::fromString('FF6F8CB0-C57D-11E1-9B21-0800200C9A66');
+        $this->assertSame('ff6f8cb0-c57d-11e1-9b21-0800200c9a66', $uuid->toString());
+    }
+
+    public function testFromStringLazyUuidFromUppercase(): void
+    {
+        $this->assertInstanceOf(LazyUuidFromString::class, Uuid::fromString('FF6F8CB0-C57D-11E1-9B21-0800200C9A66'));
+    }
+
     public function testGetBytes(): void
     {
         $uuid = Uuid::fromString('ff6f8cb0-c57d-11e1-9b21-0800200c9a66');