diff --git a/antarest/study/storage/rawstudy/model/filesystem/inode.py b/antarest/study/storage/rawstudy/model/filesystem/inode.py
index aba1e13450..d8d5a444bd 100644
--- a/antarest/study/storage/rawstudy/model/filesystem/inode.py
+++ b/antarest/study/storage/rawstudy/model/filesystem/inode.py
@@ -139,7 +139,7 @@ def get_file_content(self) -> Tuple[bytes, str, str]:
             return (
                 read_original_file_in_archive(
                     self.config.archive_path,
-                    str(self.get_relative_path_inside_archive(self.config.archive_path)),
+                    self.get_relative_path_inside_archive(self.config.archive_path),
                 ),
                 suffix,
                 filename,
@@ -147,8 +147,8 @@ def get_file_content(self) -> Tuple[bytes, str, str]:
         else:
             return self.config.path.read_bytes(), suffix, filename
 
-    def get_relative_path_inside_archive(self, archive_path: Path) -> Path:
-        return self.config.path.relative_to(archive_path.parent / self.config.study_id)
+    def get_relative_path_inside_archive(self, archive_path: Path) -> str:
+        return self.config.path.relative_to(archive_path.parent / self.config.study_id).as_posix()
 
     def _assert_url_end(self, url: Optional[List[str]] = None) -> None:
         """
diff --git a/antarest/study/storage/rawstudy/model/filesystem/matrix/input_series_matrix.py b/antarest/study/storage/rawstudy/model/filesystem/matrix/input_series_matrix.py
index a18928f488..e48aa71023 100644
--- a/antarest/study/storage/rawstudy/model/filesystem/matrix/input_series_matrix.py
+++ b/antarest/study/storage/rawstudy/model/filesystem/matrix/input_series_matrix.py
@@ -147,7 +147,7 @@ def get_file_content(self) -> t.Tuple[bytes, str, str]:
         if self.config.archive_path:
             return (
                 read_original_file_in_archive(
-                    self.config.archive_path, str(self.get_relative_path_inside_archive(self.config.archive_path))
+                    self.config.archive_path, self.get_relative_path_inside_archive(self.config.archive_path)
                 ),
                 suffix,
                 filename,