diff --git a/libs/pbd/pbd/signal.h.py b/libs/pbd/pbd/signal.h.py
index 70a1a2d88c..9997811c52 100644
--- a/libs/pbd/pbd/signal.h.py
+++ b/libs/pbd/pbd/signal.h.py
@@ -9,10 +9,7 @@ if len(sys.argv) < 2:
 f = open(sys.argv[1], 'w')
 
 print >>f,"""
-/** THIS FILE IS AUTOGENERATED: DO NOT EDIT.
- *
- *  This file is generated by signals.h.py.
- */
+/** THIS FILE IS AUTOGENERATED by signals.h.py: CHANGES WILL BE LOST */
 
 #include <list>
 #include <boost/function.hpp>
@@ -26,7 +23,7 @@ namespace PBD {
 
 class Connection;
 
-class SignalBase : public boost::enable_shared_from_this<SignalBase>
+class SignalBase
 {
 public:
 	virtual ~SignalBase () {}
@@ -39,17 +36,25 @@ protected:
 class Connection : public boost::enable_shared_from_this<Connection>
 {
 public:
-	Connection (boost::shared_ptr<SignalBase> b) : _signal (b) {}
+	Connection (SignalBase* b) : _signal (b) {}
 
 	void disconnect ()
 	{
+		boost::mutex::scoped_lock lm (_mutex);
 		if (_signal) {
 			_signal->disconnect (shared_from_this ());
 		} 
 	}
 
+	void signal_going_away ()
+	{
+		boost::mutex::scoped_lock lm (_mutex);
+		_signal = 0;
+	}
+
 private:
-	boost::shared_ptr<SignalBase> _signal;
+	boost::mutex _mutex;
+	SignalBase* _signal;
 };
 
 template<typename R>
@@ -112,10 +117,23 @@ def simple_signal(f, n, v):
 
     print >>f,"public:"
     print >>f,""
+    print >>f,"\t~SimpleSignal%d ()" % n
+
     print >>f,"""
+	{
+		boost::mutex::scoped_lock lm (_mutex);
+#if __GNUC__ > 4 || (__GNUC__ == 4 && (__GNUC_MINOR__ >= 6))                                                                      
+                for (typename Slots::iterator i = _slots.begin(); i != _slots.end(); ++i) {                                                 
+#else                                                                                                                             
+                for (Slots::iterator i = _slots.begin(); i != _slots.end(); ++i) {                                                          
+#endif                                                                                                                               
+			i->first->signal_going_away ();
+		}
+	}
+
 	boost::shared_ptr<Connection> connect (slot_function_type f)
 	{
-		boost::shared_ptr<Connection> c (new Connection (shared_from_this ()));
+		boost::shared_ptr<Connection> c (new Connection (this));
 		boost::mutex::scoped_lock lm (_mutex);
 		_slots[c] = f;
 		return c;