2 files changed, 11 insertions, 3 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index e417ff9ee86..ed9053e851a 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,5 +1,8 @@
 2007-07-10  Stefan Monnier  <monnier@iro.umontreal.ca>
 
+        * alloc.c (mark_maybe_pointer): Enforce mult-of-8 alignment when using
+        USE_LSB_TAG.  Suggested by Dmitry Antipov <dmantipov@yandex.ru>.
+
         * fns.c (map_char_table): Use an array of int for `indices' rather than
         an array of Lisp_Objects (which are only ever integers anyway).
         (Fmap_char_table): Update caller.
diff --git a/src/alloc.c b/src/alloc.c
index 7668309e59c..f3140da1ddc 100644
--- a/src/alloc.c
+++ b/src/alloc.c
@@ -4263,9 +4263,14 @@ mark_maybe_pointer (p)
 {
   struct mem_node *m;
 
-  /* Quickly rule out some values which can't point to Lisp data.  We
-     assume that Lisp data is aligned on even addresses.  */
-  if ((EMACS_INT) p & 1)
+  /* Quickly rule out some values which can't point to Lisp data.  */
+  if ((EMACS_INT) p %
+#ifdef USE_LSB_TAG
+      8 /* USE_LSB_TAG needs Lisp data to be aligned on multiples of 8.  */
+#else
+      2 /* We assume that Lisp data is aligned on even addresses.  */
+#endif
+      )
     return;
 
   m = mem_find (p);