diff --git a/basis/io/streams/byte-array/byte-array.factor b/basis/io/streams/byte-array/byte-array.factor
index b877e97cf1..16160cd42d 100644
--- a/basis/io/streams/byte-array/byte-array.factor
+++ b/basis/io/streams/byte-array/byte-array.factor
@@ -2,7 +2,7 @@
 ! See http://factorcode.org/license.txt for BSD license.
 USING: byte-arrays byte-vectors kernel io.encodings io.streams.string
 sequences io namespaces io.encodings.private accessors sequences.private
-io.streams.sequence destructors ;
+io.streams.sequence destructors math combinators ;
 IN: io.streams.byte-array
 
 : <byte-writer> ( encoding -- stream )
@@ -20,6 +20,14 @@ M: byte-reader stream-read1 sequence-read1 ;
 M: byte-reader stream-read-until sequence-read-until ;
 M: byte-reader dispose drop ;
 
+M: byte-reader stream-seek ( n seek-type stream -- )
+    swap {
+        { seek-absolute [ (>>i) ] }
+        { seek-relative [ [ + ] change-i drop ] }
+        { seek-end [ dup underlying>> length >>i [ + ] change-i drop ] }
+        [ bad-seek-type ]
+    } case ;
+
 : <byte-reader> ( byte-array encoding -- stream )
     [ B{ } like 0 byte-reader boa ] dip <decoder> ;