diff -up texinfo-4.13/info/indices.c.orig texinfo-4.13/info/indices.c
--- texinfo-4.13/info/indices.c.orig	2010-08-31 12:04:38.317462471 +0200
+++ texinfo-4.13/info/indices.c	2010-08-31 12:11:49.322624552 +0200
@@ -192,6 +192,7 @@ do_info_index_search (WINDOW *window, in
      index for, build and remember an index now. */
   fb = file_buffer_of_window (window);
   if (!initial_index_filename ||
+      !fb ||
       (FILENAME_CMP (initial_index_filename, fb->filename) != 0))
     {
       info_free_references (index_index);
@@ -287,8 +288,9 @@ index_entry_exists (WINDOW *window, char
     return 0;
 
   fb = file_buffer_of_window (window);
-  if (!initial_index_filename
-      || (FILENAME_CMP (initial_index_filename, fb->filename) != 0))
+  if (!initial_index_filename ||
+      !fb ||
+      (FILENAME_CMP (initial_index_filename, fb->filename) != 0))
     {
       info_free_references (index_index);
       index_index = info_indices_of_file_buffer (fb);