diff --git a/src/mergerfs.cpp b/src/mergerfs.cpp
index 6bbdd599..0c430b6e 100644
--- a/src/mergerfs.cpp
+++ b/src/mergerfs.cpp
@@ -408,7 +408,8 @@ main(int    argc_,
     ->expected(-1)
     ;
 
-  app.add_option("mountpoint",mountpoint);
+  app.add_option("mountpoint",mountpoint)
+    ->expected(1);
 
   try
     {