1 files changed, 5 insertions, 1 deletions

diff --git a/src/alloc.c b/src/alloc.c
index b41af98ac4f..e010f8501bc 100644
--- a/src/alloc.c
+++ b/src/alloc.c
@@ -1237,7 +1237,7 @@ LENGTH must be a number.  INIT matters only in whether it is t or nil.")
   bits_per_value = sizeof (EMACS_INT) * BITS_PER_CHAR;
 
   length_in_elts = (XFASTINT (length) + bits_per_value - 1) / bits_per_value;
-  length_in_chars = length_in_elts * sizeof (EMACS_INT);
+  length_in_chars = ((XFASTINT (length) + BITS_PER_CHAR - 1) / BITS_PER_CHAR);
 
   /* We must allocate one more elements than LENGTH_IN_ELTS for the
      slot `size' of the struct Lisp_Bool_Vector.  */
@@ -1251,6 +1251,10 @@ LENGTH must be a number.  INIT matters only in whether it is t or nil.")
   real_init = (NILP (init) ? 0 : -1);
   for (i = 0; i < length_in_chars ; i++)
     p->data[i] = real_init;
+  /* Clear the extraneous bits in the last byte.  */
+  if (XINT (length) != length_in_chars * BITS_PER_CHAR)
+    XBOOL_VECTOR (val)->data[length_in_chars - 1]
+      &= (1 << (XINT (length) % BITS_PER_CHAR)) - 1;
 
   return val;
 }