diff --git a/md5.asd b/md5.asd
index ec34697..4829f27 100755
--- a/md5.asd
+++ b/md5.asd
@@ -17,6 +17,7 @@
   :version "2.0.2"
   :depends-on (#+sbcl "sb-rotate-byte"
                #-(or :cmu :sbcl
-                     (and :lispworks (not :lispworks4)) :ccl :allegro)
-               :flexi-streams)
+                     (and :lispworks (not :lispworks4))
+                     :ccl :allegro)
+               "flexi-streams")
   :components ((:file "md5")))
diff --git a/md5.lisp b/md5.lisp
index bb54f59..05ed5d9 100755
--- a/md5.lisp
+++ b/md5.lisp
@@ -712,7 +712,11 @@ determined by the underlying implementation."
     (if (<= char-code-limit 256)
         (md5sum-sequence string :start start :end end)
         (md5sum-sequence
-         (flexi-streams:string-to-octets string)))))
+         (flexi-streams:string-to-octets string
+                                         :external-format
+                                         (if (eq external-format :default)
+                                             :UTF-8
+                                             external-format))))))
 
 (eval-when (:compile-toplevel :load-toplevel :execute)
   (defconstant +buffer-size+ (* 128 1024)