diff --git a/Tests/Unit/Domain/Service/VersionResolverTest.php b/Tests/Unit/Domain/Service/VersionResolverTest.php
index a10025e..4cf4e93 100644
--- a/Tests/Unit/Domain/Service/VersionResolverTest.php
+++ b/Tests/Unit/Domain/Service/VersionResolverTest.php
@@ -39,7 +39,7 @@ public function Can_not_extract_version_string(string $migrationClassName): void
         $this->versionResolver->extractVersion($migrationClassName);
     }
 
-    public function invalidClassNames(): array
+    public static function invalidClassNames(): array
     {
         return [
             'lower case class name' => ['version20201111145100'],
@@ -48,7 +48,7 @@ public function invalidClassNames(): array
         ];
     }
 
-    public function validClassNames(): array
+    public static function validClassNames(): array
     {
         return [
             'class name without namespace' => ['Version20190930132259', '20190930132259'],