diff --git a/src/config.in b/src/config.in
index 34bd389289a..09bc0ba6629 100644
--- a/src/config.in
+++ b/src/config.in
@@ -181,6 +181,7 @@ Boston, MA 02111-1307, USA.  */
 #undef HAVE_SETITIMER
 #undef HAVE_UALARM
 #undef HAVE_SYS_WAIT_H
+#undef HAVE_STRINGS_H
 
 #undef HAVE_LIBDNET
 #undef HAVE_LIBPTHREADS
@@ -298,6 +299,8 @@ Boston, MA 02111-1307, USA.  */
 #undef HAVE_GETPT
 #undef HAVE_SPEED_T		/* speed_t typedef in termios.h */
 #undef HAVE_STRUCT_TIMEZONE
+#undef HAVE_INDEX
+#undef HAVE_RINDEX
 
 #undef LOCALTIME_CACHE
 #undef HAVE_INET_SOCKETS