diff -aurN ardour-0.9beta9.1.orig/libs/pbd/pthread_utils.cc ardour-0.9beta9.1/libs/pbd/pthread_utils.cc
--- ardour-0.9beta9.1.orig/libs/pbd/pthread_utils.cc	2003-04-16 14:17:03.000000000 +0200
+++ ardour-0.9beta9.1/libs/pbd/pthread_utils.cc	2004-02-12 21:04:49.433392736 +0100
@@ -23,6 +23,7 @@
 #include <string>
 
 #include <pbd/pthread_utils.h>
+#include <signal.h>
 
 using std::string;
 using std::cerr;