diff --git a/Data/Histogram/Fill.hs b/Data/Histogram/Fill.hs
--- a/Data/Histogram/Fill.hs
+++ b/Data/Histogram/Fill.hs
@@ -20,7 +20,7 @@
   , (-<<)
     -- * Histogram builders
     -- ** Stateful
-  , HBuilderM
+  , HBuilderM(..)
   , feedOne
   , freezeHBuilderM
     -- ** Stateless
diff --git a/histogram-fill.cabal b/histogram-fill.cabal
--- a/histogram-fill.cabal
+++ b/histogram-fill.cabal
@@ -1,9 +1,13 @@
 Name:           histogram-fill
-Version:        0.8.0.0
+Version:        0.8.1.0
 Synopsis:       Library for histograms creation.
 Description:    
   This is library for histograms filling. Its aim to provide
   convenient way to create and fill histograms. 
+  .
+  Changes in 0.8.1.0
+  .
+  * Constructor of @HBuilderM@ exported.
   .
   Changes in 0.8.0.0
   .