diff --git a/articat/fs_artifact.py b/articat/fs_artifact.py
index 5330325..aacc180 100644
--- a/articat/fs_artifact.py
+++ b/articat/fs_artifact.py
@@ -73,9 +73,12 @@ def main_dir(self) -> str:
         """
         # to not worry about presence of scheme, we remove the prefix
         # and add it back
-        if self.files_dir:
+        if self._file_prefix is not None:
+            return self._file_prefix
+        elif self.files_dir:
             return self.files_dir
-        # TODO: remove this code path
+        # TODO: remove this code path, for this to be safe to remove
+        #       we need to update legacy artifacts first (or remove them)
         # This is the legacy handling of the main_dir, where we gather
         # main dir from the files_pattern
         assert self.files_pattern is not None
diff --git a/articat/tests/fs_artifact_test.py b/articat/tests/fs_artifact_test.py
index c579d7e..83fa5ae 100644
--- a/articat/tests/fs_artifact_test.py
+++ b/articat/tests/fs_artifact_test.py
@@ -26,6 +26,7 @@ def test_fs_artifact_join_paths_works(uid: ID) -> None:
         with fsspec.open(p, "w") as f:
             f.write("ala ma kota")
         a.files_pattern = None
+        assert a.main_dir == a.staging_file_prefix
         assert p == f"{a.staging_file_prefix}/data.dat"
     assert a._file_prefix is None
     p = a.joinpath("data.dat")