diff --git a/collects/net/base64-unit.rkt b/collects/net/base64-unit.rkt
index 8fc1d28..6fa00d4 100644
--- a/collects/net/base64-unit.rkt
+++ b/collects/net/base64-unit.rkt
@@ -1,67 +1,8 @@
-#lang racket/unit
+#lang racket/base
 
-(require "base64-sig.rkt")
+(require racket/unit
+         "base64-sig.rkt" "base64.rkt")
 
-(import)
-(export base64^)
+(define-unit-from-context base64@ base64^)
 
-(define ranges '([#"AZ" 0] [#"az" 26] [#"09" 52] [#"++" 62] [#"//" 63]))
-
-(define-values (base64-digit digit-base64)
-  (let ([bd (make-vector 256 #f)] [db (make-vector 64 #f)])
-    (for ([r ranges] #:when #t
-          [i (in-range (bytes-ref (car r) 0) (add1 (bytes-ref (car r) 1)))]
-          [n (in-naturals (cadr r))])
-      (vector-set! bd i n)
-      (vector-set! db n i))
-    (values (vector->immutable-vector bd) (vector->immutable-vector db))))
-
-(define =byte (bytes-ref #"=" 0))
-(define ones
-  (vector->immutable-vector
-   (list->vector (for/list ([i (in-range 9)]) (sub1 (arithmetic-shift 1 i))))))
-
-(define (base64-decode-stream in out)
-  (let loop ([data 0] [bits 0])
-    (if (>= bits 8)
-      (let ([bits (- bits 8)])
-        (write-byte (arithmetic-shift data (- bits)) out)
-        (loop (bitwise-and data (vector-ref ones bits)) bits))
-      (let ([c (read-byte in)])
-        (unless (or (eof-object? c) (eq? c =byte))
-          (let ([v (vector-ref base64-digit c)])
-            (if v
-              (loop (+ (arithmetic-shift data 6) v) (+ bits 6))
-              (loop data bits))))))))
-
-(define (base64-encode-stream in out [linesep #"\n"])
-  (let loop ([data 0] [bits 0] [width 0])
-    (define (write-char)
-      (write-byte (vector-ref digit-base64 (arithmetic-shift data (- 6 bits)))
-                  out)
-      (let ([width (modulo (add1 width) 72)])
-        (when (zero? width) (display linesep out))
-        width))
-    (if (>= bits 6)
-      (let ([bits (- bits 6)])
-        (loop (bitwise-and data (vector-ref ones bits)) bits (write-char)))
-      (let ([c (read-byte in)])
-        (if (eof-object? c)
-          ;; flush extra bits
-          (begin
-            (let ([width (if (> bits 0) (write-char) width)])
-              (when (> width 0)
-                (for ([i (in-range (modulo (- width) 4))])
-                  (write-byte =byte out))
-                (display linesep out))))
-          (loop (+ (arithmetic-shift data 8) c) (+ bits 8) width))))))
-
-(define (base64-decode src)
-  (let ([s (open-output-bytes)])
-    (base64-decode-stream (open-input-bytes src) s)
-    (get-output-bytes s)))
-
-(define (base64-encode src)
-  (let ([s (open-output-bytes)])
-    (base64-encode-stream (open-input-bytes src) s (bytes 13 10))
-    (get-output-bytes s)))
+(provide base64@)