diff --git a/qutebrowser/browser/browsertab.py b/qutebrowser/browser/browsertab.py
index e0435587e..2c0aa6722 100644
--- a/qutebrowser/browser/browsertab.py
+++ b/qutebrowser/browser/browsertab.py
@@ -392,7 +392,7 @@ class AbstractCaret(QObject):
     def drop_selection(self):
         raise NotImplementedError
 
-    def selection(self, callback=None):
+    def selection(self, callback):
         raise NotImplementedError
 
     def follow_selected(self, *, tab=False):
diff --git a/qutebrowser/browser/webengine/webenginetab.py b/qutebrowser/browser/webengine/webenginetab.py
index f42f01c24..dfb4d898c 100644
--- a/qutebrowser/browser/webengine/webenginetab.py
+++ b/qutebrowser/browser/webengine/webenginetab.py
@@ -289,7 +289,7 @@ class WebEngineCaret(browsertab.AbstractCaret):
     def drop_selection(self):
         self._js_call('dropSelection')
 
-    def selection(self, callback=None):
+    def selection(self, callback):
         # Not using selectedText() as WORKAROUND for
         # https://bugreports.qt.io/browse/QTBUG-53134
         # Even on Qt 5.10 selectedText() seems to work poorly, see