diff --git a/src/mergerfs.cpp b/src/mergerfs.cpp
index 516eb9c3..dcfaac75 100644
--- a/src/mergerfs.cpp
+++ b/src/mergerfs.cpp
@@ -406,9 +406,11 @@ main(int    argc_,
   app.add_option("branches",branches)
     ->delimiter(':')
     ->expected(2,-1)
+    ->required()
     ;
 
   app.add_option("mountpoint")
+    ->required()
     ;
 
   try