diff --git a/orangecontrib/text/widgets/owsemanticviewer.py b/orangecontrib/text/widgets/owsemanticviewer.py
index cb83be568..f558e8685 100644
--- a/orangecontrib/text/widgets/owsemanticviewer.py
+++ b/orangecontrib/text/widgets/owsemanticviewer.py
@@ -99,6 +99,20 @@ def __init__(self):
         self.verticalHeader().hide()
 
 
+class DocumentsModel(PyTableModel):
+    @staticmethod
+    def _argsortData(data: np.ndarray, order: Qt.SortOrder) -> np.ndarray:
+        # put NaNs last when sorting
+        if data.dtype not in (float, int):
+            data = np.char.lower(data)
+        indices = np.argsort(data, kind='mergesort')
+        if order == Qt.DescendingOrder:
+            indices = indices[::-1]
+            if data.dtype == float:
+                return np.roll(indices, -np.isnan(data).sum())
+        return indices
+
+
 class DisplayDocument:
     Document, Section, Sentence = range(3)
     ITEMS = ["Document", "Section", "Sentence"]
@@ -232,7 +246,7 @@ def _setup_gui(self):
         gui.rubber(self.controlArea)
 
         # Main area
-        model = PyTableModel(parent=self)
+        model = DocumentsModel(parent=self)
         self._list_view = SemanticListView()
         self._list_view.setModel(model)
         self._list_view.selectionModel().selectionChanged.connect(
diff --git a/orangecontrib/text/widgets/tests/test_owsemanticviewer.py b/orangecontrib/text/widgets/tests/test_owsemanticviewer.py
index 380fb4de5..3015476ed 100644
--- a/orangecontrib/text/widgets/tests/test_owsemanticviewer.py
+++ b/orangecontrib/text/widgets/tests/test_owsemanticviewer.py
@@ -3,6 +3,7 @@
 from typing import List
 from unittest.mock import Mock, patch
 
+import numpy as np
 from AnyQt.QtCore import Qt
 from AnyQt.QtTest import QSignalSpy
 from AnyQt.QtWidgets import QTableView
@@ -13,7 +14,7 @@
 from orangecontrib.text import Corpus
 from orangecontrib.text.semantic_search import SemanticSearch
 from orangecontrib.text.widgets.owsemanticviewer import OWSemanticViewer, \
-    run, DisplayDocument
+    run, DisplayDocument, DocumentsModel, SemanticListView
 
 
 def create_words_table(words: List) -> Table:
@@ -267,6 +268,41 @@ def test_display_document_sentence(self):
         self.assertEqual(new_text, text1)
 
 
+class TestDocumentsModel(WidgetTest):
+    def setUp(self):
+        self.model = model = DocumentsModel()
+        model[:] = [[1, 1, "Foo"], [1, np.nan, "Bar"], [1, 2, "Baz"]]
+
+        self.view = view = SemanticListView()
+        view.setModel(model)
+
+    def test_sort_nans(self):
+        model = self.model
+
+        self.view.sortByColumn(1, Qt.DescendingOrder)
+        self.assertEqual(model.data(model.index(0, 2)), "Baz")
+        self.assertEqual(model.data(model.index(1, 2)), "Foo")
+        self.assertEqual(model.data(model.index(2, 2)), "Bar")
+
+        self.view.sortByColumn(1, Qt.AscendingOrder)
+        self.assertEqual(model.data(model.index(0, 2)), "Foo")
+        self.assertEqual(model.data(model.index(1, 2)), "Baz")
+        self.assertEqual(model.data(model.index(2, 2)), "Bar")
+
+    def test_sort_test_column(self):
+        model = self.model
+
+        self.view.sortByColumn(2, Qt.DescendingOrder)
+        self.assertEqual(model.data(model.index(0, 2)), "Foo")
+        self.assertEqual(model.data(model.index(1, 2)), "Baz")
+        self.assertEqual(model.data(model.index(2, 2)), "Bar")
+
+        self.view.sortByColumn(2, Qt.AscendingOrder)
+        self.assertEqual(model.data(model.index(0, 2)), "Bar")
+        self.assertEqual(model.data(model.index(1, 2)), "Baz")
+        self.assertEqual(model.data(model.index(2, 2)), "Foo")
+
+
 class DummySearch(SemanticSearch):
     def __call__(self, *args, **kwargs):
         return [