diff --git a/src/earthkit/data/utils/testing.py b/src/earthkit/data/utils/testing.py
index 01e2b3a7..0214ec07 100644
--- a/src/earthkit/data/utils/testing.py
+++ b/src/earthkit/data/utils/testing.py
@@ -221,7 +221,7 @@ def load_nc_or_xr_source(path, mode):
     else:
         import xarray
 
-        return from_object(xarray.open_dataset(path)).to_fieldlist()
+        return from_object(xarray.open_dataset(path, decode_timedelta=True)).to_fieldlist()
 
 
 class ArrayBackend: