diff --git a/ChangeLog.md b/ChangeLog.md
--- a/ChangeLog.md
+++ b/ChangeLog.md
@@ -2,6 +2,10 @@
 
 ## [Unreleased]
 
+## [0.1.2.8] - 2020-03-12
+### Added
+- `instance Traversable (Sequence mk w)`.
+
 ## [0.1.2.7] - 2020-02-11
 ### Changed
 - Support GHC-8.8.
diff --git a/cobot-io.cabal b/cobot-io.cabal
--- a/cobot-io.cabal
+++ b/cobot-io.cabal
@@ -4,10 +4,10 @@
 --
 -- see: https://github.com/sol/hpack
 --
--- hash: b98bae8044cc69e013da5d57a2077a7d9b4f9330def6ecd281f524600c734fa9
+-- hash: 43e7df0f9593c9d406051c22f2a7ae31d13535e94800fe30c9a692b205071e15
 
 name:           cobot-io
-version:        0.1.2.7
+version:        0.1.2.8
 synopsis:       Biological data file formats and IO
 description:    Please see the README on GitHub at <https://github.com/less-wrong/cobot-io#readme>
 category:       Bio
diff --git a/src/Bio/Sequence/Class.hs b/src/Bio/Sequence/Class.hs
--- a/src/Bio/Sequence/Class.hs
+++ b/src/Bio/Sequence/Class.hs
@@ -87,6 +87,9 @@
 
   length = V.length . _sequ
 
+instance Traversable (Sequence mk w) where
+  traverse f s@Sequence{..} = fmap (\newSeq -> s { _sequ = newSeq }) $ traverse f _sequ
+
 -- | Exported constructor for 'Sequence'. Should be used ONLY in module Bio.Sequence.
 --
 _sequenceInner :: Vector a -> [(mk, Range)] -> Vector w -> Sequence mk w a