diff --git a/e4rat/src/signals.hh b/e4rat/src/signals.hh

index f050adf..222c38c 100644

--- a/e4rat/src/signals.hh

+++ b/e4rat/src/signals.hh

@@ -40,6 +40,7 @@

  * }

  */

 #include <boost/signals2/signal.hpp>

+#include <boost/bind.hpp>

 //get the number of arguments

 #define BIND1ST _1