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