diff --git a/tests/HelperTest.php b/tests/HelperTest.php
index 63ced1d..20aa485 100644
--- a/tests/HelperTest.php
+++ b/tests/HelperTest.php
@@ -56,6 +56,9 @@ public function testGetHttpContentTypeForUrl(string $faviconUrl, ?string $expect
         $this->assertSame($expectedContentType, Helper::getHttpContentTypeForUrl($faviconUrl, new Client()));
     }
 
+    /**
+     * @return array<string, array<string|null>>
+     */
     public static function faviconProvider(): array
     {
         return [