diff --git a/src/ikarus.boot b/src/ikarus.boot
index cb1cebb..a1dd0b4 100644
Binary files a/src/ikarus.boot and b/src/ikarus.boot differ
diff --git a/src/ikarus.strings.ss b/src/ikarus.strings.ss
index 7fbfe85..0b65e8b 100644
--- a/src/ikarus.strings.ss
+++ b/src/ikarus.strings.ss
@@ -2,7 +2,7 @@
 (library (ikarus strings)
   (export string-length string-ref string-set! make-string string->list string=?
           string-append substring string list->string uuid
-          string-copy string-for-each)
+          string-copy string-for-each string-fill!)
   (import 
     (ikarus system $strings)
     (ikarus system $fx)
@@ -11,7 +11,8 @@
     (ikarus system $pairs)
     (except (ikarus) string-length string-ref string-set! make-string
             string->list string=? string-append substring string
-            list->string uuid string-copy string-for-each))
+            list->string uuid string-copy string-for-each
+            string-fill!))
 
 
   (define string-length
@@ -62,7 +63,7 @@
           [(n) 
            (unless (and (fixnum? n) (fx>= n 0))
              (error 'make-string "~s is not a valid length" n))
-           ($make-string n)]
+           (fill! ($make-string n) 0 n (integer->char 0))]
           [(n c)
            (unless (and (fixnum? n) (fx>= n 0))
              (error 'make-string "~s is not a valid length" n))
@@ -300,6 +301,16 @@
                               (f i ($cdr v*))))))
                 (f p v0 v1 v* ($fxadd1 i) n)])))])))
 
+  (define (string-fill! v fill)
+    (unless (string? v) 
+      (error 'string-fill! "~s is not a vector" v))
+    (unless (char? fill)
+      (error 'string-fill! "~s is not a character" fill))
+    (let f ([v v] [i 0] [n ($string-length v)] [fill fill])
+      (unless ($fx= i n) 
+        ($string-set! v i fill)
+        (f v ($fxadd1 i) n fill))))
+
   (define uuid
     (lambda ()
       (let ([s ($make-bytevector 16)])
diff --git a/src/ikarus.vectors.ss b/src/ikarus.vectors.ss
index 34b42e8..343fcc8 100644
--- a/src/ikarus.vectors.ss
+++ b/src/ikarus.vectors.ss
@@ -1,11 +1,13 @@
 
 (library (ikarus vectors)
   (export make-vector vector vector-length vector-ref vector-set!
-          vector->list list->vector vector-map vector-for-each)
+          vector->list list->vector vector-map vector-for-each
+          vector-fill!)
   (import 
     (except (ikarus) make-vector vector 
             vector-length vector-ref vector-set!
-            vector->list list->vector vector-map vector-for-each)
+            vector->list list->vector vector-map vector-for-each
+            vector-fill!)
     (ikarus system $fx)
     (ikarus system $pairs)
     (ikarus system $vectors))
@@ -252,4 +254,13 @@
                         (cons ($vector-ref ($car v*) i) 
                               (f i ($cdr v*))))))
                 (f p v0 v1 v* ($fxadd1 i) n)])))])))
+
+  (define (vector-fill! v fill)
+    (unless (vector? v) 
+      (error 'vector-fill! "~s is not a vector" v))
+    (let f ([v v] [i 0] [n ($vector-length v)] [fill fill])
+      (unless ($fx= i n) 
+        ($vector-set! v i fill)
+        (f v ($fxadd1 i) n fill))))
+
   )
diff --git a/src/makefile.ss b/src/makefile.ss
index 38a9a72..93e28f6 100755
--- a/src/makefile.ss
+++ b/src/makefile.ss
@@ -342,6 +342,7 @@
     [make-string             i r]
     [string-ref              i r]
     [string-set!             i r]
+    [string-fill!            i r]
     [string-length           i r]
     [string=?                i r]
     [string-ci=?             i unicode]
@@ -358,6 +359,7 @@
     [make-vector             i r]
     [vector-ref              i r]
     [vector-set!             i r]
+    [vector-fill!            i r]
     [vector?                 i r]
     [vector-length           i r]
     [list->vector            i r]
diff --git a/src/todo-r6rs.ss b/src/todo-r6rs.ss
index 4d16007..7d139d4 100755
--- a/src/todo-r6rs.ss
+++ b/src/todo-r6rs.ss
@@ -224,7 +224,7 @@
     [values                                     C ba se]
     [vector                                     C ba se]
     [vector->list                               C ba se]
-    [vector-fill!                               S ba se]
+    [vector-fill!                               C ba se]
     [vector-for-each                            C ba]
     [vector-length                              C ba se]
     [vector-map                                 C ba]
@@ -524,7 +524,7 @@
     [set-cdr!                                   C mp se]
     ;;;
     [string-set!                                C ms se]
-    [string-fill!                               S ms se]
+    [string-fill!                               C ms se]
     ;;;
     [command-line                               C pr]
     [exit                                       C pr]