diff --git a/cal_tools/cal_tools/tools.py b/cal_tools/cal_tools/tools.py
index a22a89cb1ec584af1b8fac28c70ee98f0aa0c97b..49febfd9f5ca0b2bdb7fa75bfa5aedfe5fad756d 100644
--- a/cal_tools/cal_tools/tools.py
+++ b/cal_tools/cal_tools/tools.py
@@ -12,6 +12,7 @@ from typing import Optional
 from urllib.parse import urljoin
 
 import dateutil.parser
+import h5py
 import ipykernel
 from metadata_client.metadata_client import MetadataClient
 from notebook.notebookapp import list_running_servers
@@ -264,12 +265,12 @@ def get_dir_creation_date(directory: str, run: int,
         try:
             dates = []
             for f in directory.glob('*.h5'):
-                with h5py.File(f) as fin:
+                with h5py.File(f, 'r') as fin:
                     cdate = fin['METADATA/creationDate'][0].decode()
                     cdate = datetime.datetime.strptime(cdate, "%Y%m%dT%H%M%SZ")
                     dates.append(cdate)
             return min(dates)
-        except IOError:
+        except (IOError, ValueError):
             ntries -= 1
 
     msg = 'Could not get the creation time from the directory'
diff --git a/tests/test_cal_tools.py b/tests/test_cal_tools.py
new file mode 100644
index 0000000000000000000000000000000000000000..e93a75174d18b4e46c0b9739db8977499f307119
--- /dev/null
+++ b/tests/test_cal_tools.py
@@ -0,0 +1,17 @@
+from datetime import datetime
+from pathlib import Path
+
+import pytest
+from cal_tools.tools import get_dir_creation_date
+
+
+def test_dir_creation_date():
+    folder = "/gpfs/exfel/exp/DETLAB/202031/p900172/raw"
+
+    date = get_dir_creation_date(folder, 10)
+    assert isinstance(date, datetime)
+    assert str(date) == '2020-07-20 10:39:03'
+
+    with pytest.raises(ValueError) as e:
+        assert get_dir_creation_date(folder, 4)
+    assert e.value.args[1] == Path(folder) / 'r0004'