--- src/tla/libarch/namespace_orig.c	2004-03-21 16:35:21.000000000 +0100
+++ src/tla/libarch/namespace.c	2004-03-21 16:31:28.000000000 +0100
@@ -1061,7 +1061,7 @@
 }
 
 
-#define char_is_alnum_or_dash(c) (char_is_alnum (c) || (c == '-'))
+#define char_is_alnum_or_dash(c) (char_is_alnum (c) || (c == '-') || (c == '_'))
 
 static t_uchar *
 over_archive_name (t_uchar * in)