diff --git a/NEWS b/NEWS
index 68e5d08f0..386e5fd76 100644
--- a/NEWS
+++ b/NEWS
@@ -26,6 +26,10 @@ more consistent with other bitvector procedures.
 These replace bitvector-set!, for similar reasons as the bitvector-ref
 replacement above.
 
+** New bitvector-set-all-bits!, bitvector-clear-all-bits! procedures
+
+These replace bitvector-fill!.
+
 ** New bitvector-set-bits!, bitvector-clear-bits! procedures
 
 These replace the wonky "bit-set*!" procedure.  See "Bit Vectors" in the
@@ -46,6 +50,10 @@ Use 'bitvector-bit-set?' or 'bitvector-bit-clear?' instead.
 
 Use 'bitvector-set-bit!' or 'bitvector-clear-bit!' instead.
 
+** 'bitvector-fill!' deprecated
+
+Use 'bitvector-set-all-bits!' or 'bitvector-clear-all-bits!' instead.
+
 ** 'bit-set*!' deprecated
 
 Use 'bitvector-set-bits!' or 'bitvector-clear-bits!' instead.
diff --git a/doc/ref/api-data.texi b/doc/ref/api-data.texi
index 141b214d8..f9b14d13f 100644
--- a/doc/ref/api-data.texi
+++ b/doc/ref/api-data.texi
@@ -6593,22 +6593,21 @@ Set (for @code{bitvector-set-bit!}) or clear (for
 @var{vec}.
 @end deffn
 
-@deftypefn {C Function} void scm_bitvector_set_bit_x (SCM vec, size_t idx)
-@deftypefnx {C Function} void scm_bitvector_clear_bit_x (SCM vec, size_t idx)
+@deftypefn {C Function} void scm_c_bitvector_set_bit_x (SCM vec, size_t idx)
+@deftypefnx {C Function} void scm_c_bitvector_clear_bit_x (SCM vec, size_t idx)
 Set or clear the bit at index @var{idx} of the bitvector @var{vec}.
 @end deftypefn
 
-@deftypefn {C Function} SCM scm_c_bitvector_set_x (SCM vec, size_t idx, SCM val)
-Set the element at index @var{idx} of the bitvector
-@var{vec} when @var{val} is true, else clear it.
-@end deftypefn
-
-@deffn {Scheme Procedure} bitvector-fill! vec val
-@deffnx {C Function} scm_bitvector_fill_x (vec, val)
-Set all elements of the bitvector
-@var{vec} when @var{val} is true, else clear them.
+@deffn {Scheme Procedure} bitvector-set-all-bits! vec
+@deffnx {Scheme Procedure} bitvector-clear-all-bits! vec
+Set or clear all bits of @var{vec}.
 @end deffn
 
+@deftypefn {C Function} void scm_c_bitvector_set_all_bits_x (SCM vec)
+@deftypefnx {C Function} void scm_c_bitvector_clear_all_bits_x (SCM vec)
+Set or clear all bits in the bitvector @var{vec}.
+@end deftypefn
+
 @deffn {Scheme Procedure} list->bitvector list
 @deffnx {C Function} scm_list_to_bitvector (list)
 Return a new bitvector initialized with the elements
diff --git a/libguile/bitvectors.c b/libguile/bitvectors.c
index 87ad6e84a..077bc556c 100644
--- a/libguile/bitvectors.c
+++ b/libguile/bitvectors.c
@@ -149,10 +149,10 @@ scm_c_make_bitvector (size_t len, SCM fill)
 				    "bitvector");
   res = scm_double_cell (scm_tc7_bitvector, len, (scm_t_bits)bits, 0);
 
-  if (!SCM_UNBNDP (fill))
-    scm_bitvector_fill_x (res, fill);
+  if (SCM_UNBNDP (fill) || !scm_is_true (fill))
+    scm_c_bitvector_clear_all_bits_x (res);
   else
-    memset (bits, 0, sizeof (uint32_t) * word_len);
+    scm_c_bitvector_set_all_bits_x (res);
       
   return res;
 }
@@ -344,57 +344,60 @@ SCM_DEFINE_STATIC (scm_bitvector_clear_bit_x, "bitvector-clear-bit!", 2, 0, 0,
 }
 #undef FUNC_NAME
 
-SCM_DEFINE (scm_bitvector_fill_x, "bitvector-fill!", 2, 0, 0,
-	    (SCM vec, SCM val),
-	    "Set all elements of the bitvector\n"
-	    "@var{vec} when @var{val} is true, else clear them.")
-#define FUNC_NAME s_scm_bitvector_fill_x
+void
+scm_c_bitvector_set_all_bits_x (SCM bv)
+#define FUNC_NAME "bitvector-set-all-bits!"
 {
-  if (IS_MUTABLE_BITVECTOR (vec))
+  VALIDATE_MUTABLE_BITVECTOR (1, bv);
+  size_t len = BITVECTOR_LENGTH (bv);
+
+  if (len > 0)
     {
-      size_t len = BITVECTOR_LENGTH (vec);
+      uint32_t *bits = BITVECTOR_BITS (bv);
+      size_t word_len = (len + 31) / 32;
+      uint32_t last_mask =  ((uint32_t)-1) >> (32*word_len - len);
 
-      if (len > 0)
-        {
-          uint32_t *bits = BITVECTOR_BITS (vec);
-          size_t word_len = (len + 31) / 32;
-          uint32_t last_mask =  ((uint32_t)-1) >> (32*word_len - len);
-
-          if (scm_is_true (val))
-            {
-              memset (bits, 0xFF, sizeof(uint32_t)*(word_len-1));
-              bits[word_len-1] |= last_mask;
-            }
-          else
-            {
-              memset (bits, 0x00, sizeof(uint32_t)*(word_len-1));
-              bits[word_len-1] &= ~last_mask;
-            }
-        }
+      memset (bits, 0xFF, sizeof(uint32_t)*(word_len-1));
+      bits[word_len-1] |= last_mask;
     }
-  else
-    {
-      scm_t_array_handle handle;
-      size_t off, len;
-      ssize_t inc;
-
-      scm_bitvector_writable_elements (vec, &handle, &off, &len, &inc);
-
-      scm_c_issue_deprecation_warning
-        ("Using bitvector-fill! on arrays is deprecated.  "
-         "Use array-set! instead.");
-
-      size_t i;
-      for (i = 0; i < len; i++)
-	scm_array_handle_set (&handle, i*inc, val);
-
-      scm_array_handle_release (&handle);
-    }
-
-  return SCM_UNSPECIFIED;
 }
 #undef FUNC_NAME
 
+void
+scm_c_bitvector_clear_all_bits_x (SCM bv)
+#define FUNC_NAME "bitvector-clear-all-bits!"
+{
+  VALIDATE_MUTABLE_BITVECTOR (1, bv);
+  size_t len = BITVECTOR_LENGTH (bv);
+
+  if (len > 0)
+    {
+      uint32_t *bits = BITVECTOR_BITS (bv);
+      size_t word_len = (len + 31) / 32;
+      uint32_t last_mask =  ((uint32_t)-1) >> (32*word_len - len);
+
+      memset (bits, 0x00, sizeof(uint32_t)*(word_len-1));
+      bits[word_len-1] &= ~last_mask;
+    }
+}
+#undef FUNC_NAME
+
+SCM_DEFINE_STATIC (scm_bitvector_set_all_bits_x,
+                   "bitvector-set-all-bits!", 1, 0, 0, (SCM vec),
+                   "Set all elements of the bitvector @var{vec}.")
+{
+  scm_c_bitvector_set_all_bits_x (vec);
+  return SCM_UNSPECIFIED;
+}
+
+SCM_DEFINE_STATIC (scm_bitvector_clear_all_bits_x,
+                   "bitvector-clear-all-bits!", 1, 0, 0, (SCM vec),
+                   "Clear all elements of the bitvector @var{vec}.")
+{
+  scm_c_bitvector_clear_all_bits_x (vec);
+  return SCM_UNSPECIFIED;
+}
+
 SCM_DEFINE (scm_list_to_bitvector, "list->bitvector", 1, 0, 0,
 	    (SCM list),
 	    "Return a new bitvector initialized with the elements\n"
diff --git a/libguile/bitvectors.h b/libguile/bitvectors.h
index 7061d3848..ffeb5a894 100644
--- a/libguile/bitvectors.h
+++ b/libguile/bitvectors.h
@@ -38,7 +38,6 @@ SCM_API SCM scm_make_bitvector (SCM len, SCM fill);
 SCM_API SCM scm_bitvector_length (SCM vec);
 SCM_API SCM scm_list_to_bitvector (SCM list);
 SCM_API SCM scm_bitvector_to_list (SCM vec);
-SCM_API SCM scm_bitvector_fill_x (SCM vec, SCM val);
 
 SCM_API SCM scm_bitvector_count (SCM v);
 SCM_API SCM scm_bitvector_position (SCM v, SCM item, SCM start);
@@ -55,6 +54,8 @@ SCM_API int scm_c_bitvector_bit_is_set (SCM vec, size_t idx);
 SCM_API int scm_c_bitvector_bit_is_clear (SCM vec, size_t idx);
 SCM_API void scm_c_bitvector_set_bit_x (SCM vec, size_t idx);
 SCM_API void scm_c_bitvector_clear_bit_x (SCM vec, size_t idx);
+SCM_API void scm_c_bitvector_set_all_bits_x (SCM vec);
+SCM_API void scm_c_bitvector_clear_all_bits_x (SCM vec);
 SCM_API const uint32_t *scm_array_handle_bit_elements (scm_t_array_handle *h);
 SCM_API uint32_t *scm_array_handle_bit_writable_elements (scm_t_array_handle *h);
 SCM_API size_t scm_array_handle_bit_elements_offset (scm_t_array_handle *h);
diff --git a/libguile/deprecated.c b/libguile/deprecated.c
index 24a50ee3b..3682a0c04 100644
--- a/libguile/deprecated.c
+++ b/libguile/deprecated.c
@@ -170,6 +170,42 @@ SCM_DEFINE (scm_bitvector_set_x, "bitvector-set!", 3, 0, 0,
 }
 #undef FUNC_NAME
 
+SCM_DEFINE (scm_bitvector_fill_x, "bitvector-fill!", 2, 0, 0,
+	    (SCM vec, SCM val),
+	    "Set all elements of the bitvector\n"
+	    "@var{vec} when @var{val} is true, else clear them.")
+#define FUNC_NAME s_scm_bitvector_fill_x
+{
+  scm_c_issue_deprecation_warning
+    ("bitvector-fill! is deprecated.  Use bitvector-set-all-bits! or "
+     "bitvector-clear-all-bits! instead.");
+
+  if (scm_is_bitvector (vec))
+    {
+      if (scm_is_true (val))
+        scm_c_bitvector_set_all_bits_x (vec);
+      else
+        scm_c_bitvector_clear_all_bits_x (vec);
+
+      return SCM_UNSPECIFIED;
+    }
+
+  scm_t_array_handle handle;
+  size_t off, len;
+  ssize_t inc;
+
+  scm_bitvector_writable_elements (vec, &handle, &off, &len, &inc);
+
+  size_t i;
+  for (i = 0; i < len; i++)
+    scm_array_handle_set (&handle, i*inc, val);
+
+  scm_array_handle_release (&handle);
+
+  return SCM_UNSPECIFIED;
+}
+#undef FUNC_NAME
+
 SCM_DEFINE (scm_bit_count, "bit-count", 2, 0, 0,
 	    (SCM b, SCM bitvector),
 	    "Return the number of occurrences of the boolean @var{b} in\n"
diff --git a/libguile/deprecated.h b/libguile/deprecated.h
index a2438310b..a0ccac75d 100644
--- a/libguile/deprecated.h
+++ b/libguile/deprecated.h
@@ -119,6 +119,7 @@ SCM_DEPRECATED SCM scm_c_bitvector_ref (SCM vec, size_t idx);
 SCM_DEPRECATED SCM scm_bitvector_ref (SCM vec, SCM idx);
 SCM_DEPRECATED void scm_c_bitvector_set_x (SCM vec, size_t idx, SCM val);
 SCM_DEPRECATED SCM scm_bitvector_set_x (SCM vec, SCM idx, SCM val);
+SCM_DEPRECATED SCM scm_bitvector_fill_x (SCM vec, SCM val);
 SCM_DEPRECATED SCM scm_bit_count (SCM item, SCM seq);
 SCM_DEPRECATED SCM scm_bit_position (SCM item, SCM v, SCM k);
 SCM_DEPRECATED SCM scm_bit_set_star_x (SCM v, SCM kv, SCM obj);
diff --git a/module/ice-9/sandbox.scm b/module/ice-9/sandbox.scm
index 86d8cbadd..75c7f0dc3 100644
--- a/module/ice-9/sandbox.scm
+++ b/module/ice-9/sandbox.scm
@@ -1095,7 +1095,8 @@ allocation limit is exceeded, an exception will be thrown to the
      bit-invert!
      bitvector-clear-bit!
      bitvector-clear-bits!
-     bitvector-fill!
+     bitvector-set-all-bits!
+     bitvector-clear-all-bits!
      bitvector-set-bit!
      bitvector-set-bits!)))
 
diff --git a/module/system/vm/frame.scm b/module/system/vm/frame.scm
index 112187e8f..18987d994 100644
--- a/module/system/vm/frame.scm
+++ b/module/system/vm/frame.scm
@@ -224,7 +224,7 @@
          (outv (make-vector len #f))
          (tmp (make-bitvector (vector-length defs) #f)))
     (define (bitvector-copy! dst src)
-      (bitvector-fill! dst #f)
+      (bitvector-clear-all-bits! dst)
       (bitvector-set-bits! dst src))
     (define (bitvector-meet! accum src)
       (bitvector-copy! tmp src)
@@ -245,7 +245,9 @@
               (kill (vector-ref killv n))
               (gen (vector-ref genv n)))
           (let ((out-count (or changed? (bitvector-count out))))
-            (bitvector-fill! in (not (zero? n)))
+            (if (zero? n)
+                (bitvector-clear-all-bits! in)
+                (bitvector-set-all-bits! in))
             (let lp ((preds (vector-ref preds n)))
               (match preds
                 (() #t)
diff --git a/test-suite/tests/bitvectors.test b/test-suite/tests/bitvectors.test
index 87b201b7a..9bbd6e2ac 100644
--- a/test-suite/tests/bitvectors.test
+++ b/test-suite/tests/bitvectors.test
@@ -25,7 +25,6 @@
   (pass-if (array? #*1010101010))
   (pass-if (eq? (array-type #*1010101010) 'b)))
 
-
 (with-test-prefix "equality"
   (pass-if (equal? #*1010101 #*1010101))
   (pass-if (array-equal? #*1010101 #*1010101))
@@ -57,6 +56,14 @@
       (array-set! bv #t 0)
       (pass-if (eqv? (array-ref bv 0) #t)))))
 
+(with-test-prefix "all bits"
+  (let ((bv (make-bitvector 5)))
+    (pass-if-equal #*00000 bv)
+    (bitvector-set-all-bits! bv)
+    (pass-if-equal #*11111 bv)
+    (bitvector-clear-all-bits! bv)
+    (pass-if-equal #*00000 bv)))
+
 (with-test-prefix "bitvector-set-bits!"
   (pass-if "#t"
     (let ((v (bitvector #t #t #f #f)))