diff --git a/comicapi/archivers/folder.py b/comicapi/archivers/folder.py
index c0292dc..ec94a3a 100644
--- a/comicapi/archivers/folder.py
+++ b/comicapi/archivers/folder.py
@@ -93,5 +93,5 @@ class FolderArchiver(Archiver):
         return "Folder"
 
     @classmethod
-    def is_valid(cls, path: pathlib.Path | str) -> bool:
-        return os.path.isdir(path)
+    def is_valid(cls, path: pathlib.Path) -> bool:
+        return path.is_dir()
diff --git a/comicapi/archivers/rar.py b/comicapi/archivers/rar.py
index 84537ae..96cbff9 100644
--- a/comicapi/archivers/rar.py
+++ b/comicapi/archivers/rar.py
@@ -246,7 +246,7 @@ class RarArchiver(Archiver):
         return "RAR"
 
     @classmethod
-    def is_valid(cls, path: pathlib.Path | str) -> bool:
+    def is_valid(cls, path: pathlib.Path) -> bool:
         if rar_support:
             return rarfile.is_rarfile(str(path))
         return False
diff --git a/comicapi/archivers/sevenzip.py b/comicapi/archivers/sevenzip.py
index a8b574c..be6e059 100644
--- a/comicapi/archivers/sevenzip.py
+++ b/comicapi/archivers/sevenzip.py
@@ -127,5 +127,5 @@ class SevenZipArchiver(Archiver):
         return "Seven Zip"
 
     @classmethod
-    def is_valid(cls, path: pathlib.Path | str) -> bool:
+    def is_valid(cls, path: pathlib.Path) -> bool:
         return py7zr.is_7zfile(path)
diff --git a/comicapi/archivers/zip.py b/comicapi/archivers/zip.py
index 0ab8941..afc7ffa 100644
--- a/comicapi/archivers/zip.py
+++ b/comicapi/archivers/zip.py
@@ -129,7 +129,7 @@ class ZipArchiver(Archiver):
         return "ZIP"
 
     @classmethod
-    def is_valid(cls, path: pathlib.Path | str) -> bool:
+    def is_valid(cls, path: pathlib.Path) -> bool:
         return zipfile.is_zipfile(path)
 
     def write_zip_comment(self, filename: pathlib.Path | str, comment: str) -> bool: