diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,9 @@
 # Revision history for monadic-recursion-schemes
 
+## 0.1.6.1 -- 2020-05-15
+
+* bugfix: export preproM and postproM.
+
 ## 0.1.6.0 -- 2020-05-15
 
 * add preproM and postproM.
diff --git a/monadic-recursion-schemes.cabal b/monadic-recursion-schemes.cabal
--- a/monadic-recursion-schemes.cabal
+++ b/monadic-recursion-schemes.cabal
@@ -4,7 +4,7 @@
 -- http://haskell.org/cabal/users-guide/
 
 name:                monadic-recursion-schemes
-version:             0.1.6.0
+version:             0.1.6.1
 synopsis:            Recursion Schemes for Monadic version.
 description:         Yet another recursion schemes for monadic style, depends on recursion-schemes.
 homepage:            https://github.com/cutsea110/monadic-recursion-schemes.git
diff --git a/src/Data/Functor/Foldable/Monadic.hs b/src/Data/Functor/Foldable/Monadic.hs
--- a/src/Data/Functor/Foldable/Monadic.hs
+++ b/src/Data/Functor/Foldable/Monadic.hs
@@ -21,6 +21,7 @@
   , dynaM'', codynaM''
   , mutuM, comutuM
   , mutuM', comutuM'
+  , preproM, postproM
   ) where
 
 import           Control.Comonad              (Comonad (..))