diff --git a/qutebrowser/completion/completionwidget.py b/qutebrowser/completion/completionwidget.py
index 9fc1ef5d7..41ed65d74 100644
--- a/qutebrowser/completion/completionwidget.py
+++ b/qutebrowser/completion/completionwidget.py
@@ -193,9 +193,8 @@ class CompletionView(QTreeView):
             prev: True for prev item, False for next one.
         """
         idx = self._next_idx(prev)
-        qtutils.ensure_valid(idx)
-        self.selectionModel().setCurrentIndex(
-            idx, QItemSelectionModel.ClearAndSelect | QItemSelectionModel.Rows)
+        self.selectionModel().setCurrentIndex(idx,
+            QItemSelectionModel.ClearAndSelect | QItemSelectionModel.Rows)
 
     def set_model(self, model):
         """Switch completion to a new model.
diff --git a/tests/unit/completion/test_completionwidget.py b/tests/unit/completion/test_completionwidget.py
index 9e7bf04bf..fb1241b2c 100644
--- a/tests/unit/completion/test_completionwidget.py
+++ b/tests/unit/completion/test_completionwidget.py
@@ -119,6 +119,8 @@ def test_maybe_resize_completion(completionview, config_stub, qtbot):
     ([['Aa'], []], -1, 'Aa'),
     ([['Aa'], [], []], 1, 'Aa'),
     ([['Aa'], [], []], -1, 'Aa'),
+    ([[]], 1, None),
+    ([[]], -1, None),
 ])
 def test_completion_item_next_prev(tree, count, expected, completionview):
     """Test that on_next_prev_item moves the selection properly.