diff --git a/cccli/command/expert.py b/cccli/command/expert.py
index 5d46e5e393f7da8cb575e57a8b88acab8e4b4d92..1ed92d2e93fa1f3d6f435f2dcc35dfed6fdf7953 100644
--- a/cccli/command/expert.py
+++ b/cccli/command/expert.py
@@ -14,6 +14,8 @@ class Command_expert(Command):
     '''Switch in expert mode'''
 
     def __call__(self, argv):
+        if len(argv) != 1:
+            raise cmdBadArgument()
         h = list(self.printer.history)
         self.printer.history.read(self.cli.settings.get("expert", ""))
         try: