diff --git a/qutebrowser/commands/runners.py b/qutebrowser/commands/runners.py
index 970fbadbe..ea10520dc 100644
--- a/qutebrowser/commands/runners.py
+++ b/qutebrowser/commands/runners.py
@@ -174,15 +174,6 @@ class CommandRunner(QObject):
             count = None
         return (count, cmdstr)
 
-    def _parse_fallback(self, text, count, keep):
-        """Parse the given commandline without a valid command."""
-        if keep:
-            cmdstr, sep, argstr = text.partition(' ')
-            cmdline = [cmdstr, sep] + argstr.split()
-        else:
-            cmdline = text.split()
-        return ParseResult(cmd=None, args=None, cmdline=cmdline, count=count)
-
     def parse(self, text, *, fallback=False, keep=False):
         """Split the commandline text into command and arguments.
 
@@ -210,7 +201,9 @@ class CommandRunner(QObject):
             if not fallback:
                 raise cmdexc.NoSuchCommandError(
                     '{}: no such command'.format(cmdstr))
-            return self._parse_fallback(text, count, keep)
+            cmdline = split.split(text, keep=keep)
+            return ParseResult(cmd=None, args=None, cmdline=cmdline,
+                               count=count)
 
         args = self._split_args(cmd, argstr, keep)
         if keep and args:
diff --git a/tests/unit/completion/test_completer.py b/tests/unit/completion/test_completer.py
index 233ba5307..6bc651d4f 100644
--- a/tests/unit/completion/test_completer.py
+++ b/tests/unit/completion/test_completer.py
@@ -176,6 +176,7 @@ def _set_cmd_prompt(cmd, txt):
                                            usertypes.Completion.command)),
     (':set -t -p |', usertypes.Completion.section),
     (':open -- |', None),
+    (':gibberish nonesense |', None),
 ])
 def test_update_completion(txt, expected, status_command_stub, completer_obj,
                            completion_widget_stub):