diff --git a/mlair/data_handler/data_handler_with_filter.py b/mlair/data_handler/data_handler_with_filter.py
index 740642fe1c2f9f8e5d748b0585241fecab68dc19..b3274b6981c675794a99f1fdd9330990ceb251be 100644
--- a/mlair/data_handler/data_handler_with_filter.py
+++ b/mlair/data_handler/data_handler_with_filter.py
@@ -39,8 +39,7 @@ str_or_list = Union[str, List[str]]
 class DataHandlerFilterSingleStation(DataHandlerSingleStation):
     """General data handler for a single station to be used by a superior data handler."""
 
-    # _requirements = remove_items(inspect.getfullargspec(DataHandlerSingleStation).args, ["self", "station"])
-    _requirements = DataHandlerSingleStation.requirements()
+    _requirements = remove_items(DataHandlerSingleStation.requirements(), "station")
     _hash = DataHandlerSingleStation._hash + ["filter_dim"]
 
     DEFAULT_FILTER_DIM = "filter"
@@ -107,8 +106,7 @@ class DataHandlerFilterSingleStation(DataHandlerSingleStation):
 class DataHandlerFirFilterSingleStation(DataHandlerFilterSingleStation):
     """Data handler for a single station to be used by a superior data handler. Inputs are FIR filtered."""
 
-    # _requirements = remove_items(inspect.getfullargspec(DataHandlerFilterSingleStation).args, ["self", "station"])
-    _requirements = DataHandlerFilterSingleStation.requirements()
+    _requirements = remove_items(DataHandlerFilterSingleStation.requirements(), "station")
     _hash = DataHandlerFilterSingleStation._hash + ["filter_cutoff_period", "filter_order", "filter_window_type",
                                                     "filter_add_unfiltered"]
 
diff --git a/test/test_data_handler/test_data_handler_mixed_sampling.py b/test/test_data_handler/test_data_handler_mixed_sampling.py
index 56751c44120ce41c5994d59eb06c800ce29ca56b..7418a435008f06a9016f903fe140b51d0a7c8106 100644
--- a/test/test_data_handler/test_data_handler_mixed_sampling.py
+++ b/test/test_data_handler/test_data_handler_mixed_sampling.py
@@ -4,7 +4,7 @@ __date__ = '2020-12-10'
 from mlair.data_handler.data_handler_mixed_sampling import DataHandlerMixedSampling, \
     DataHandlerMixedSamplingSingleStation, DataHandlerMixedSamplingWithKzFilter, \
     DataHandlerMixedSamplingWithKzFilterSingleStation, DataHandlerSeparationOfScales, \
-    DataHandlerSeparationOfScalesSingleStation
+    DataHandlerSeparationOfScalesSingleStation, DataHandlerMixedSamplingWithFilterSingleStation
 from mlair.data_handler.data_handler_with_filter import DataHandlerKzFilterSingleStation
 from mlair.data_handler.data_handler_single_station import DataHandlerSingleStation
 from mlair.helpers import remove_items
@@ -86,7 +86,7 @@ class TestDataHandlerMixedSamplingSingleStation:
         pass
 
 
-class TestDataHandlerMixedSamplingWithFilter:
+class TestDataHandlerMixedSamplingWithKzFilter:
 
     def test_data_handler(self):
         obj = object.__new__(DataHandlerMixedSamplingWithKzFilter)
@@ -98,7 +98,7 @@ class TestDataHandlerMixedSamplingWithFilter:
 
     def test_requirements(self):
         obj = object.__new__(DataHandlerMixedSamplingWithKzFilter)
-        req1 = object.__new__(DataHandlerMixedSamplingSingleStation)
+        req1 = object.__new__(DataHandlerMixedSamplingWithFilterSingleStation)
         req2 = object.__new__(DataHandlerKzFilterSingleStation)
         req = list(set(req1.requirements() + req2.requirements()))
         assert sorted(obj._requirements) == sorted(remove_items(req, "station"))
@@ -120,7 +120,7 @@ class TestDataHandlerSeparationOfScales:
 
     def test_requirements(self):
         obj = object.__new__(DataHandlerMixedSamplingWithKzFilter)
-        req1 = object.__new__(DataHandlerMixedSamplingSingleStation)
+        req1 = object.__new__(DataHandlerMixedSamplingWithFilterSingleStation)
         req2 = object.__new__(DataHandlerKzFilterSingleStation)
         req = list(set(req1.requirements() + req2.requirements()))
         assert sorted(obj._requirements) == sorted(remove_items(req, "station"))