diff --git a/libguile/bytevectors.c b/libguile/bytevectors.c
index 7dfdab499..00aab6911 100644
--- a/libguile/bytevectors.c
+++ b/libguile/bytevectors.c
@@ -196,10 +196,15 @@
   SCM_SET_BYTEVECTOR_FLAGS ((bv), SCM_BYTEVECTOR_FLAGS (bv) | flag)
 #define SCM_BYTEVECTOR_SET_LENGTH(_bv, _len)            \
   SCM_SET_CELL_WORD_1 ((_bv), (scm_t_bits) (_len))
-#define SCM_BYTEVECTOR_SET_CONTENTS(_bv, _contents)	\
-  SCM_SET_CELL_WORD_2 ((_bv), (scm_t_bits) (_contents))
+#define SCM_BYTEVECTOR_SET_CONTENTS(_bv, _contents)             \
+  do                                                            \
+    {                                                           \
+      SCM_SET_CELL_WORD_2 ((_bv), scm_tc7_pointer);             \
+      SCM_SET_CELL_WORD_3 ((_bv), (scm_t_bits) (_contents));    \
+    }                                                           \
+  while (0)
 #define SCM_BYTEVECTOR_SET_PARENT(_bv, _parent)	\
-  SCM_SET_CELL_OBJECT_3 ((_bv), (_parent))
+  SCM_SET_CELL_OBJECT ((_bv), 4, (_parent))
 
 #define SCM_VALIDATE_MUTABLE_BYTEVECTOR(pos, v) \
   SCM_MAKE_VALIDATE_MSG (pos, v, MUTABLE_BYTEVECTOR_P, "mutable bytevector")
diff --git a/libguile/bytevectors.h b/libguile/bytevectors.h
index 980d6e267..77a0ef2f3 100644
--- a/libguile/bytevectors.h
+++ b/libguile/bytevectors.h
@@ -1,7 +1,7 @@
 #ifndef SCM_BYTEVECTORS_H
 #define SCM_BYTEVECTORS_H
 
-/* Copyright 2009,2011,2018
+/* Copyright 2009,2011,2018,2019
      Free Software Foundation, Inc.
 
    This file is part of Guile.
@@ -26,20 +26,23 @@
 #include "libguile/gc.h"
 
 #include "libguile/uniform.h"
+#include "libguile/foreign.h"
 
 
 /* R6RS bytevectors.  */
 
 /* The size in words of the bytevector header (type tag and flags, length,
    and pointer to the underlying buffer).  */
-#define SCM_BYTEVECTOR_HEADER_SIZE   4U
+#define SCM_BYTEVECTOR_HEADER_SIZE   5U
 
 #define SCM_BYTEVECTOR_LENGTH(_bv)		\
   ((size_t) SCM_CELL_WORD_1 (_bv))
+#define SCM_BYTEVECTOR_POINTER(_bv)             \
+  (SCM_PACK_POINTER (SCM_CELL_OBJECT_LOC ((_bv), 2)))
 #define SCM_BYTEVECTOR_CONTENTS(_bv)		\
-  ((signed char *) SCM_CELL_WORD_2 (_bv))
+  ((signed char *) SCM_POINTER_VALUE (SCM_BYTEVECTOR_POINTER (_bv)))
 #define SCM_BYTEVECTOR_PARENT(_bv)		\
-  (SCM_CELL_OBJECT_3 (_bv))
+  (SCM_CELL_OBJECT_4 (_bv))
 
 
 SCM_API SCM scm_endianness_big;
diff --git a/libguile/foreign.c b/libguile/foreign.c
index 1368cc9da..1879c23bc 100644
--- a/libguile/foreign.c
+++ b/libguile/foreign.c
@@ -1,4 +1,4 @@
-/* Copyright 2010-2016,2018
+/* Copyright 2010-2016,2018,2019
      Free Software Foundation, Inc.
 
    This file is part of Guile.
@@ -313,8 +313,15 @@ SCM_DEFINE (scm_bytevector_to_pointer, "bytevector->pointer", 1, 1, 0,
     boffset = scm_to_unsigned_integer (offset, 0,
                                        SCM_BYTEVECTOR_LENGTH (bv) - 1);
 
-  ret = scm_from_pointer (ptr + boffset, NULL);
-  register_weak_reference (ret, bv);
+  if (boffset == 0)
+    /* The fast path: return the pre-allocated pointer.  */
+    ret = SCM_BYTEVECTOR_POINTER (bv);
+  else
+    {
+      ret = scm_from_pointer (ptr + boffset, NULL);
+      register_weak_reference (ret, bv);
+    }
+
   return ret;
 }
 #undef FUNC_NAME
diff --git a/module/language/tree-il/compile-cps.scm b/module/language/tree-il/compile-cps.scm
index 8f048a504..c164f606b 100644
--- a/module/language/tree-il/compile-cps.scm
+++ b/module/language/tree-il/compile-cps.scm
@@ -883,7 +883,7 @@
                (letk k ($kargs ('ptr) (ptr) ,body))
                (build-term
                  ($continue k src
-                   ($primcall 'pointer-ref/immediate '(bytevector . 2)
+                   ($primcall 'pointer-ref/immediate '(bytevector . 3)
                               (bv))))))))
     (letk k ($kargs ('rlen) (rlen) ,access))
     (letk kassume
diff --git a/module/system/base/types.scm b/module/system/base/types.scm
index 418c9fed4..438aee9df 100644
--- a/module/system/base/types.scm
+++ b/module/system/base/types.scm
@@ -1,5 +1,5 @@
 ;;; 'SCM' type tag decoding.
-;;; Copyright (C) 2014, 2015, 2017, 2018 Free Software Foundation, Inc.
+;;; Copyright (C) 2014, 2015, 2017, 2018, 2019 Free Software Foundation, Inc.
 ;;;
 ;;; This library is free software; you can redistribute it and/or modify it
 ;;; under the terms of the GNU Lesser General Public License as published by
@@ -415,7 +415,7 @@ using BACKEND."
                                                 (match (native-endianness)
                                                   ('little "UTF-32LE")
                                                   ('big "UTF-32BE")))))
-          (((_ & #x7f = %tc7-bytevector) len address)
+          (((_ & #x7f = %tc7-bytevector) len pointer-tag address)
            (let ((bv-port (memory-port backend address len)))
              (get-bytevector-n bv-port len)))
           ((((len << 8) || %tc7-vector))