1 files changed, 5 insertions, 1 deletions

diff --git a/Tools/make_index b/Tools/make_index
index f9cddb25902f..f2ba2895aa8f 100644
--- a/Tools/make_index
+++ b/Tools/make_index
@@ -25,7 +25,11 @@ sub by_path {
   # Collapse all the '..' sequences.
     my @f = split('/', $name), @p = ();
     foreach (@f) { (/\.\./) ? pop(@p) : push(@p, $_); }
-    return $by_path{join('/', @p)};
+    $name = join('/', @p);
+    return $by_path{$name} if (defined $by_path{$name});
+
+    print STDERR "make_index: no entry for: $name\n";
+    return undef;
 }
 
 # This routine replaces what used to be the time-consuming