diff -pur dbus-glib-0.74/dbus/dbus-gproxy.c dbus-glib-0.74.new/dbus/dbus-gproxy.c
--- dbus-glib-0.74/dbus/dbus-gproxy.c	2007-04-20 19:36:09.000000000 +0300
+++ dbus-glib-0.74.new/dbus/dbus-gproxy.c	2007-10-19 16:43:34.990501168 +0300
@@ -2167,7 +2167,11 @@ dbus_g_proxy_begin_call_internal (DBusGP
                                         timeout))
     goto oom;
   dbus_message_unref (message);
-  g_assert (pending != NULL);
+  if (pending == NULL)
+    {
+      g_debug ("Disconnected");
+      return 0;
+    }
 
   call_id = ++priv->call_id_counter;
 
@@ -2526,8 +2530,18 @@ dbus_g_proxy_call (DBusGProxy        *pr
 
   g_value_array_free (in_args);
 
-  first_arg_type = va_arg (args, GType);
-  ret = dbus_g_proxy_end_call_internal (proxy, call_id, error, first_arg_type, args);
+  if (call_id > 0)
+    {
+      first_arg_type = va_arg (args, GType);
+      ret = dbus_g_proxy_end_call_internal (proxy, call_id, error, first_arg_type, args);
+    }
+  else
+    {
+      g_set_error (error, DBUS_GERROR,
+		   DBUS_GERROR_FAILED,
+		   _("Disconnection or out-of-memory"));
+      ret = FALSE;
+    }
 
   va_end (args);