diff --git a/mantidimaging/eyes_tests/reconstruct_window_test.py b/mantidimaging/eyes_tests/reconstruct_window_test.py
index 8f8557b59a1..902b715d3fd 100644
--- a/mantidimaging/eyes_tests/reconstruct_window_test.py
+++ b/mantidimaging/eyes_tests/reconstruct_window_test.py
@@ -8,7 +8,7 @@
 
 from mantidimaging.eyes_tests.base_eyes import BaseEyesTest
 from mantidimaging.test_helpers.unit_test_helper import generate_images
-from mantidimaging.core.data.dataset import MixedDataset
+from mantidimaging.core.data.dataset import Dataset
 from mantidimaging.test_helpers.qt_test_helpers import wait_until
 
 
@@ -56,7 +56,7 @@ def test_reconstruction_window_reconstruct_tab(self):
     def test_negative_nan_overlay(self):
         images = generate_images(seed=10)
         images.name = "bad_data"
-        ds = MixedDataset(stacks=[images])
+        ds = Dataset(stacks=[images])
         self.imaging.presenter.model.add_dataset_to_model(ds)
         self.imaging.presenter.create_single_tabbed_images_stack(images)
         QApplication.sendPostedEvents()
diff --git a/mantidimaging/gui/widgets/dataset_selector/test/presenter_test.py b/mantidimaging/gui/widgets/dataset_selector/test/presenter_test.py
index d5373c41553..5b08cdf0f96 100644
--- a/mantidimaging/gui/widgets/dataset_selector/test/presenter_test.py
+++ b/mantidimaging/gui/widgets/dataset_selector/test/presenter_test.py
@@ -5,7 +5,7 @@
 import unittest
 from unittest import mock
 
-from mantidimaging.core.data.dataset import StrictDataset, MixedDataset
+from mantidimaging.core.data.dataset import StrictDataset, Dataset
 from mantidimaging.gui.widgets.dataset_selector.presenter import DatasetSelectorWidgetPresenter, Notification
 from mantidimaging.gui.widgets.dataset_selector.view import DatasetSelectorWidgetView
 
@@ -33,7 +33,7 @@ def setUp(self) -> None:
         self.ds1.name = "Dataset 1"
         self.ds2 = StrictDataset(sample=self.img2, flat_before=self.img3)
         self.ds2.name = "Dataset 2"
-        self.ds3 = MixedDataset(stacks=[self.img4])
+        self.ds3 = Dataset(stacks=[self.img4])
         self.ds3.name = "Dataset 3"
 
     def test_handle_selection_no_matching_index_found(self):
diff --git a/mantidimaging/gui/windows/spectrum_viewer/test/presenter_test.py b/mantidimaging/gui/windows/spectrum_viewer/test/presenter_test.py
index a6fb345fd5c..01953fe8686 100644
--- a/mantidimaging/gui/windows/spectrum_viewer/test/presenter_test.py
+++ b/mantidimaging/gui/windows/spectrum_viewer/test/presenter_test.py
@@ -10,7 +10,7 @@
 from PyQt5.QtWidgets import QPushButton, QActionGroup, QGroupBox, QAction, QCheckBox, QTabWidget
 from parameterized import parameterized
 
-from mantidimaging.core.data.dataset import StrictDataset, MixedDataset
+from mantidimaging.core.data.dataset import StrictDataset, Dataset
 from mantidimaging.core.utility.sensible_roi import SensibleROI
 from mantidimaging.gui.windows.main import MainWindowView
 from mantidimaging.gui.windows.spectrum_viewer import SpectrumViewerWindowView, SpectrumViewerWindowPresenter
@@ -103,9 +103,9 @@ def test_handle_sample_change_dataset_unchanged(self):
         self.presenter.main_window.get_dataset.assert_not_called()
         self.assertEqual(self.view.current_dataset_id, initial_dataset_id)
 
-    def test_handle_sample_change_to_MixedDataset(self):
+    def test_handle_sample_change_to_dataset_no_sample(self):
         self.presenter.get_dataset_id_for_stack = mock.Mock(return_value=uuid.uuid4())
-        new_dataset = MixedDataset(stacks=[generate_images()])
+        new_dataset = Dataset(stacks=[generate_images()])
         self.presenter.main_window.get_dataset = mock.Mock(return_value=new_dataset)
         self.presenter.main_window.get_stack = mock.Mock(return_value=generate_images())
         self.presenter.show_new_sample = mock.Mock()