diff --git a/src/commands/CmdUndo.cpp b/src/commands/CmdUndo.cpp
index a5ed130f4..908d06bd0 100644
--- a/src/commands/CmdUndo.cpp
+++ b/src/commands/CmdUndo.cpp
@@ -45,9 +45,8 @@ CmdUndo::CmdUndo ()
 int CmdUndo::execute (std::string& output)
 {
   // Detect attempts to modify the task.
-  for (auto& a : context.cli._args)
-    if (a.hasTag ("MODIFICATION"))
-      throw std::string (STRING_CMD_UNDO_MODS);
+  if (context.cli2.getWords ().size ())
+    throw std::string (STRING_CMD_UNDO_MODS);
 
   context.tdb2.revert ();
   return 0;