--- libidn-1.31-vanilla/src/idn.c	2015-07-07 22:59:35.000000000 +0200
+++ libidn-1.31/src/idn.c	2015-07-09 09:47:36.239549144 +0200
@@ -202,8 +202,9 @@
 	  error (EXIT_FAILURE, errno, _("input error"));
 	}
 
-      if (readbuf[strlen (readbuf) - 1] == '\n')
-	readbuf[strlen (readbuf) - 1] = '\0';
+      if (strlen (readbuf) > 0)
+	if (readbuf[strlen (readbuf) - 1] == '\n')
+	  readbuf[strlen (readbuf) - 1] = '\0';
 
       if (args_info.stringprep_given)
 	{