diff --git a/lib/compass/exec/helpers.rb b/lib/compass/exec/helpers.rb
index b10e2311..be77022c 100644
--- a/lib/compass/exec/helpers.rb
+++ b/lib/compass/exec/helpers.rb
@@ -5,6 +5,7 @@ module Compass::Exec
       if Compass::Commands.command_exists? arguments.first
         SubCommandUI
       else
+        Haml::Util.haml_warn "WARNING: This interface is deprecated. Please use the new subcommand interface.\nSee `compass help` for more information.\n"
         SwitchUI
       end
     end