--- gsmlib-1.10/gsmlib/gsm_unix_serial.h~	2002-09-22 13:51:10.000000000 +0200
+++ gsmlib-1.10/gsmlib/gsm_unix_serial.h	2004-03-14 04:16:26.000000000 +0100
@@ -13,6 +13,7 @@
 #ifndef GSM_UNIX_SERIAL_H
 #define GSM_UNIX_SERIAL_H
 
+#include <cassert>
 #include <string>
 #include <gsmlib/gsm_error.h>
 #include <gsmlib/gsm_port.h>