diff --git a/mu4e/mu4e-mark.el b/mu4e/mu4e-mark.el
index e98bbf39..88e139f5 100644
--- a/mu4e/mu4e-mark.el
+++ b/mu4e/mu4e-mark.el
@@ -377,7 +377,7 @@ user which one)."
         (mu4e-error "Target dir %s does not exist " fulltarget)
       target)))
 
-(defun mu4e-mark-execute-all (no-confirmation)
+(defun mu4e-mark-execute-all (&optional no-confirmation)
   "Execute the actions for all marked messages in this buffer.
 After the actions have been executed successfully, the affected
 messages are *hidden* from the current header list. Since the