diff --git a/lib/sl/ss.h b/lib/sl/ss.h
index 24a036c39..debc6d95f 100644
--- a/lib/sl/ss.h
+++ b/lib/sl/ss.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1998 Kungliga Tekniska Högskolan
+ * Copyright (c) 1998 - 2000 Kungliga Tekniska Högskolan
  * (Royal Institute of Technology, Stockholm, Sweden). 
  * All rights reserved. 
  *
@@ -52,4 +52,6 @@ int ss_listen (int);
 void ss_perror (int, long, const char*);
 int ss_quit (int argc, char**);
 
+#define SS_ET_COMMAND_NOT_FOUND (-1)
+
 #endif /* __ss_h__ */