--- guile.c.~2.3.~	2012-01-16 04:32:49.000000000 +0100
+++ guile.c	2012-01-17 23:35:53.000000000 +0100
@@ -92,9 +92,12 @@ func_guile (char *o, char **argv, const
   if (argv[0] && argv[0][0] != '\0')
     {
       char *str = scm_with_guile (internal_guile_eval, argv[0]);
+      if (str != NULL)
+	{
       o = variable_buffer_output (o, str, strlen (str));
       free (str);
     }
+    }
 
   return o;
 }