diff --git a/qutebrowser/browser/webengine/webenginetab.py b/qutebrowser/browser/webengine/webenginetab.py
index f1857327b..6206a7774 100644
--- a/qutebrowser/browser/webengine/webenginetab.py
+++ b/qutebrowser/browser/webengine/webenginetab.py
@@ -706,7 +706,9 @@ class WebEngineTab(browsertab.AbstractTab):
         self._widget.shutdown()
 
     def reload(self, *, force=False):
-        self.predicted_navigation.emit(self.url())
+        if self.url().isValid():
+            self.predicted_navigation.emit(self.url())
+
         if force:
             action = QWebEnginePage.ReloadAndBypassCache
         else:
@@ -931,6 +933,7 @@ class WebEngineTab(browsertab.AbstractTab):
     @pyqtSlot(QUrl)
     def _on_predicted_navigation(self, url):
         """If we know we're going to visit an URL soon, change the settings."""
+        qtutils.ensure_valid(url)
         self.settings.update_for_url(url)
 
     @pyqtSlot(usertypes.NavigationRequest)
diff --git a/qutebrowser/browser/webkit/webkittab.py b/qutebrowser/browser/webkit/webkittab.py
index 422645e61..934fdb3c3 100644
--- a/qutebrowser/browser/webkit/webkittab.py
+++ b/qutebrowser/browser/webkit/webkittab.py
@@ -701,7 +701,9 @@ class WebKitTab(browsertab.AbstractTab):
         self._widget.shutdown()
 
     def reload(self, *, force=False):
-        self.predicted_navigation.emit(self.url())
+        if self.url().isValid():
+            self.predicted_navigation.emit(self.url())
+
         if force:
             action = QWebPage.ReloadAndBypassCache
         else:
diff --git a/qutebrowser/config/websettings.py b/qutebrowser/config/websettings.py
index c069f7d56..cfb53e658 100644
--- a/qutebrowser/config/websettings.py
+++ b/qutebrowser/config/websettings.py
@@ -22,7 +22,7 @@
 from PyQt5.QtGui import QFont
 
 from qutebrowser.config import config, configutils
-from qutebrowser.utils import log, usertypes, urlmatch
+from qutebrowser.utils import log, usertypes, urlmatch, qtutils
 from qutebrowser.misc import objects
 
 UNSET = object()
@@ -141,6 +141,7 @@ class AbstractSettings:
         Return:
             A set of settings which actually changed.
         """
+        qtutils.ensure_valid(url)
         changed_settings = set()
         for values in config.instance:
             if not values.opt.supports_pattern: