diff --git a/supirfactor_dynamical/datasets/stratified_file_dataset.py b/supirfactor_dynamical/datasets/stratified_file_dataset.py
index 41ed408..5e8d310 100644
--- a/supirfactor_dynamical/datasets/stratified_file_dataset.py
+++ b/supirfactor_dynamical/datasets/stratified_file_dataset.py
@@ -67,7 +67,8 @@ def load_file(
                     _H5ADFileLoader.load_layer(
                         file_handle,
                         _elayer,
-                        obs_include_mask
+                        obs_include_mask,
+                        feature_mask=feature_mask
                     )
                     for _elayer in extra_layers
                 ]
@@ -366,7 +367,8 @@ def __init__(
             layer=file_data_layer,
             extra_layers=yield_extra_layers,
             append_obs=True,
-            obs_include_mask=obs_include_mask
+            obs_include_mask=obs_include_mask,
+            feature_mask=feature_mask
         )
         self.yields_tuple = len(self.loaded_data) > 1
 
diff --git a/supirfactor_dynamical/tests/test_loader_h5ad.py b/supirfactor_dynamical/tests/test_loader_h5ad.py
index 6fff91a..c3b70bc 100644
--- a/supirfactor_dynamical/tests/test_loader_h5ad.py
+++ b/supirfactor_dynamical/tests/test_loader_h5ad.py
@@ -789,6 +789,52 @@ def test_load_h5(self):
             [3, 3, 3, 3]
         )
 
+    def test_combine_class(self):
+
+        dataset = StratifySingleFileDataset(
+            self.filename,
+            ['strat'],
+            yield_obs_cats=['strat'],
+            combine_categories={'D': 'C'},
+            random_state=10
+        )
+
+        self.assertEqual(
+            len(dataset.loaded_data),
+            2
+        )
+
+        self.assertEqual(
+            len(dataset.loaded_data[0]),
+            100
+        )
+
+        self.assertEqual(
+            [32, 32, 36],
+            list(map(len, dataset.stratification_group_indexes))
+        )
+
+        _classes = []
+
+        for i, (v, c) in enumerate(dataset):
+            self.assertEqual(
+                v.shape,
+                (4,)
+            )
+            self.assertEqual(
+                c.shape,
+                (4,)
+            )
+            _classes.append(c)
+
+        _classes = np.vstack(_classes).sum(0).astype(int)
+        self.assertEqual(i, 95)
+
+        npt.assert_equal(
+            _classes,
+            [32, 32, 29, 3]
+        )
+
     def test_h5_mask(self):
 
         dataset = StratifySingleFileDataset(