diff --git a/qutebrowser/browser/browsertab.py b/qutebrowser/browser/browsertab.py
index 62fb67453..14d5c0e8d 100644
--- a/qutebrowser/browser/browsertab.py
+++ b/qutebrowser/browser/browsertab.py
@@ -793,7 +793,7 @@ class AbstractTab(QWidget):
     def icon(self):
         raise NotImplementedError
 
-    def set_html(self, html, base_url):
+    def set_html(self, html, base_url=QUrl()):
         raise NotImplementedError
 
     def networkaccessmanager(self):
diff --git a/qutebrowser/browser/commands.py b/qutebrowser/browser/commands.py
index f513651cb..f70b72a32 100644
--- a/qutebrowser/browser/commands.py
+++ b/qutebrowser/browser/commands.py
@@ -1375,13 +1375,8 @@ class CommandDispatcher:
             formatter = pygments.formatters.HtmlFormatter(full=True,
                                                           linenos='table')
             highlighted = pygments.highlight(source, lexer, formatter)
-            try:
-                current_url = self._current_url()
-            except cmdexc.CommandError as e:
-                message.error(str(e))
-                return
             new_tab = self._tabbed_browser.tabopen()
-            new_tab.set_html(highlighted, current_url)
+            new_tab.set_html(highlighted)
             new_tab.data.viewing_source = True
 
         tab.dump_async(show_source_cb)
diff --git a/qutebrowser/browser/history.py b/qutebrowser/browser/history.py
index 294425549..d05d4b01c 100644
--- a/qutebrowser/browser/history.py
+++ b/qutebrowser/browser/history.py
@@ -257,6 +257,10 @@ class WebHistory(QObject):
     @pyqtSlot(QUrl, QUrl, str)
     def add_from_tab(self, url, requested_url, title):
         """Add a new history entry as slot, called from a BrowserTab."""
+        if url.isEmpty():
+            # things set via setHtml
+            return
+
         no_formatting = QUrl.UrlFormattingOption(0)
         if (requested_url.isValid() and
                 not requested_url.matches(url, no_formatting)):
diff --git a/qutebrowser/browser/webengine/webenginetab.py b/qutebrowser/browser/webengine/webenginetab.py
index af93786d6..6d6177733 100644
--- a/qutebrowser/browser/webengine/webenginetab.py
+++ b/qutebrowser/browser/webengine/webenginetab.py
@@ -626,14 +626,12 @@ class WebEngineTab(browsertab.AbstractTab):
     def icon(self):
         return self._widget.icon()
 
-    def set_html(self, html, base_url=None):
+    def set_html(self, html, base_url=QUrl()):
         # FIXME:qtwebengine
         # check this and raise an exception if too big:
         # Warning: The content will be percent encoded before being sent to the
         # renderer via IPC. This may increase its size. The maximum size of the
         # percent encoded content is 2 megabytes minus 30 bytes.
-        if base_url is None:
-            base_url = QUrl()
         self._widget.setHtml(html, base_url)
 
     def networkaccessmanager(self):
diff --git a/qutebrowser/browser/webkit/webkittab.py b/qutebrowser/browser/webkit/webkittab.py
index daf46a503..5d3d8e87a 100644
--- a/qutebrowser/browser/webkit/webkittab.py
+++ b/qutebrowser/browser/webkit/webkittab.py
@@ -710,7 +710,7 @@ class WebKitTab(browsertab.AbstractTab):
         requested_url = self.url(requested=True)
         self.add_history_item.emit(url, requested_url, self.title())
 
-    def set_html(self, html, base_url):
+    def set_html(self, html, base_url=QUrl()):
         self._widget.setHtml(html, base_url)
 
     def networkaccessmanager(self):