--- signal/signal.orig	2013-12-26 12:39:10 UTC
+++ signal/signal
@@ -1,6 +1,10 @@
 #ifndef INCLUDED_SIGNAL_
 #define INCLUDED_SIGNAL_
 
+#if defined(__FreeBSD__) || defined(__DragonFly__)
+#include <cstdlib>
+#endif
+
 #include <vector>
 #include <signal.h>