diff --git a/Orange/widgets/visualize/owbarplot.py b/Orange/widgets/visualize/owbarplot.py
index 9d9e9dcac54..45ec95eade6 100644
--- a/Orange/widgets/visualize/owbarplot.py
+++ b/Orange/widgets/visualize/owbarplot.py
@@ -572,7 +572,10 @@ def get_labels(self) -> Optional[Union[List, np.ndarray]]:
         elif not self.annot_var:
             return []
         elif self.annot_var == self.enumeration:
-            return np.arange(1, len(self.data) + 1)[self.grouped_indices]
+            return [
+                str(x)
+                for x in np.arange(1, len(self.data) + 1)[self.grouped_indices]
+            ]
         else:
             return [self.annot_var.str_val(row[self.annot_var])
                     for row in self.grouped_data]
diff --git a/Orange/widgets/visualize/tests/test_owbarplot.py b/Orange/widgets/visualize/tests/test_owbarplot.py
index 0ff75962a85..f3294b3bb19 100644
--- a/Orange/widgets/visualize/tests/test_owbarplot.py
+++ b/Orange/widgets/visualize/tests/test_owbarplot.py
@@ -137,6 +137,21 @@ def test_group_axis(self):
         self.assertFalse(group_axis.isVisible())
         self.assertFalse(annot_axis.isVisible())
 
+    def test_annotate_by_enumeration(self):
+        widget = self.widget
+
+        self.send_signal(widget.Inputs.data, self.data)
+        combo = widget.controls.annot_var
+        for i in range(combo.count()):
+            try:
+                simulate.combobox_activate_index(combo, i)
+            except AssertionError:  # skip disabled items
+                pass
+            else:
+                labels = widget.get_labels()
+                self.assertTrue(not labels
+                                or all(isinstance(x, str) for x in labels))
+
     def test_datasets(self):
         controls = self.widget.controls
         for ds in datasets.datasets():