diff --git a/src/physiotwin4d/data_download_tools.py b/src/physiotwin4d/data_download_tools.py
index da83d37..480c0c2 100644
--- a/src/physiotwin4d/data_download_tools.py
+++ b/src/physiotwin4d/data_download_tools.py
@@ -245,7 +245,7 @@ def DownloadCHOPValve4DData(dirname: Union[str, Path]) -> Path:  # noqa: N802
         data_dir = Path(dirname)
         for subdir_name, asset_name in DataDownloadTools.CHOP_VALVE4D_ASSETS.items():
             target_dir = data_dir / subdir_name
-            if DataDownloadTools._CHOPValve4DSubdirIsPopulated(subdir_name, target_dir):
+            if DataDownloadTools._CHOPValve4DSubdirIsPopulated(target_dir):
                 continue
             url = DataDownloadTools.CHOP_VALVE4D_RELEASE_URL + asset_name
             DataDownloadTools._DownloadAndExtractZip(url, target_dir)
@@ -254,7 +254,7 @@ def DownloadCHOPValve4DData(dirname: Union[str, Path]) -> Path:  # noqa: N802
 
     @staticmethod
     def _CHOPValve4DSubdirIsPopulated(  # noqa: N802
-        subdir_name: str, target_dir: Path
+        target_dir: Path,
     ) -> bool:
         """Return True when ``target_dir`` already has subdir_name's expected files.
 
@@ -266,6 +266,7 @@ def _CHOPValve4DSubdirIsPopulated(  # noqa: N802
         """
         if not target_dir.is_dir():
             return False
+        subdir_name = target_dir.name
         if subdir_name == "CT":
             has_ct_volume = any(
                 (target_dir / filename).is_file()
@@ -293,7 +294,7 @@ def _DownloadAndExtractZip(url: str, target_dir: Path) -> None:  # noqa: N802
                 raise RuntimeError(f"Downloaded archive is empty: {url}")
 
             with zipfile.ZipFile(archive_file) as archive:
-                archive.extractall(target_dir)
+                archive.extractall(target_dir.parent)
 
     @staticmethod
     def VerifyCHOPValve4DData(dirname: Union[str, Path]) -> bool:  # noqa: N802
@@ -304,13 +305,11 @@ def VerifyCHOPValve4DData(dirname: Union[str, Path]) -> bool:  # noqa: N802
         experiments.
         """
         data_dir = Path(dirname)
-        has_ct = DataDownloadTools._CHOPValve4DSubdirIsPopulated("CT", data_dir / "CT")
+        has_ct = DataDownloadTools._CHOPValve4DSubdirIsPopulated(data_dir / "CT")
         has_alterra = DataDownloadTools._CHOPValve4DSubdirIsPopulated(
-            "Alterra", data_dir / "Alterra"
-        )
-        has_tpv25 = DataDownloadTools._CHOPValve4DSubdirIsPopulated(
-            "TPV25", data_dir / "TPV25"
+            data_dir / "Alterra"
         )
+        has_tpv25 = DataDownloadTools._CHOPValve4DSubdirIsPopulated(data_dir / "TPV25")
         return has_ct or (has_alterra and has_tpv25)
 
     @staticmethod
diff --git a/tests/test_download_heart_data.py b/tests/test_download_heart_data.py
index 0143e6c..e63e8ef 100644
--- a/tests/test_download_heart_data.py
+++ b/tests/test_download_heart_data.py
@@ -200,7 +200,9 @@ def make_archive(subdir_name: str, member_name: str, content: bytes) -> Path:
         for subdir_name, asset_name in DataDownloadTools.CHOP_VALVE4D_ASSETS.items():
             url = DataDownloadTools.CHOP_VALVE4D_RELEASE_URL + asset_name
             urls_to_archives[url] = make_archive(
-                subdir_name, f"{subdir_name}.txt", f"# {subdir_name}\n".encode()
+                subdir_name,
+                f"{subdir_name}/{subdir_name}.txt",
+                f"# {subdir_name}\n".encode(),
             )
 
         def fake_urlopen(url: str, timeout: float) -> object:
@@ -274,9 +276,9 @@ def make_archive(subdir_name: str, member_name: str, content: bytes) -> Path:
         urls_to_archives = {}
         for subdir_name, asset_name in DataDownloadTools.CHOP_VALVE4D_ASSETS.items():
             url = DataDownloadTools.CHOP_VALVE4D_RELEASE_URL + asset_name
-            member_name = "RVOT28-Dias.mha" if subdir_name == "CT" else "frame_0000.vtk"
+            leaf = "RVOT28-Dias.mha" if subdir_name == "CT" else "frame_0000.vtk"
             urls_to_archives[url] = make_archive(
-                subdir_name, member_name, f"# {subdir_name}\n".encode()
+                subdir_name, f"{subdir_name}/{leaf}", f"# {subdir_name}\n".encode()
             )
 
         def fake_urlopen(url: str, timeout: float) -> object: