diff --git a/ChangeLog b/ChangeLog
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+Changes in 0.8.3.0
+
+  * Constraints are relaxed from `PrimMonad' to `Monad' wherever possible in
+    Data.Histogram.Fill module.
+
+
 Changes in 0.8.2.0
 
   * Smart constructors for BinF and BinD check that bin number is not
diff --git a/Data/Histogram/Bin/Classes.hs b/Data/Histogram/Bin/Classes.hs
--- a/Data/Histogram/Bin/Classes.hs
+++ b/Data/Histogram/Bin/Classes.hs
@@ -108,7 +108,10 @@
   unsafeSliceBin :: Int -> Int -> b -> b
 
 -- | Slice bin using indices
-sliceBin :: SliceableBin b => Int -> Int -> b -> b
+sliceBin :: SliceableBin b
+         => Int                 -- ^ Index of first bin
+         -> Int                 -- ^ Index of last bin
+         -> b -> b
 sliceBin i j b 
   | i < 0  ||  j < 0  ||  i > j  ||  i >= n  ||  j >= n = error "sliceBin: bad slice"
   | otherwise                                           = unsafeSliceBin i j b
diff --git a/Data/Histogram/Fill.hs b/Data/Histogram/Fill.hs
--- a/Data/Histogram/Fill.hs
+++ b/Data/Histogram/Fill.hs
@@ -214,15 +214,15 @@
                                  }
 
 -- | Builders modified using 'HistBuilder' API will share same buffer.
-instance PrimMonad m => HistBuilder (HBuilderM m) where
+instance Monad m => HistBuilder (HBuilderM m) where
     modifyIn      f      h = h { hbInput  = hbInput h . f }
     addCut        f      h = h { hbInput  = \x -> when (f x) (hbInput h x) }
     fromContainer fmapM_ h = h { hbInput  = fmapM_ (hbInput h) }
     modifyOut     f      h = h { hbOutput = f `liftM` hbOutput h }
 
-instance PrimMonad m => Functor (HBuilderM m a) where
+instance Monad m => Functor (HBuilderM m a) where
     fmap = modifyOut
-instance PrimMonad m => Applicative (HBuilderM m a) where
+instance Monad m => Applicative (HBuilderM m a) where
     pure x = HBuilderM { hbInput  = const $ return ()
                        , hbOutput = return x
                        }
@@ -232,7 +232,7 @@
                                         return (a b)
                         }
 
-instance (PrimMonad m, Monoid b) => Monoid (HBuilderM m a b) where
+instance (Monad m, Monoid b) => Monoid (HBuilderM m a b) where
     mempty = HBuilderM { hbInput  = \_ -> return ()
                        , hbOutput = return mempty
                        }
@@ -243,13 +243,13 @@
 
 
 -- | Put one item into histogram
-feedOne :: PrimMonad m => HBuilderM m a b -> a -> m ()
+feedOne :: Monad m => HBuilderM m a b -> a -> m ()
 feedOne = hbInput
 {-# INLINE feedOne #-}
 
 -- | Extract result from histogram builder. It's safe to call this
 --   function multiple times and mutate builder afterwards.
-freezeHBuilderM :: PrimMonad m => HBuilderM m a b -> m b
+freezeHBuilderM :: Monad m => HBuilderM m a b -> m b
 freezeHBuilderM = hbOutput
 {-# INLINE freezeHBuilderM #-}
 
@@ -389,7 +389,7 @@
 -- | Create stateful histogram builder. Output function should be safe
 --   to call multiple times and builder could be modified afterwards.
 --   So functions like @unsafeFreeze@ from @vector@ couldn't be used.
-mkStatefulBuilder :: PrimMonad m
+mkStatefulBuilder :: Monad m
                   => (a -> m ()) -- ^ Add value to accumulator
                   -> m b         -- ^ Extract result from accumulator
                   -> HBuilderM m a b
@@ -448,13 +448,13 @@
 ----------------------------------------------------------------
 
 -- | Join histogram builders in container
-joinHBuilderM :: (F.Traversable f, PrimMonad m) => f (HBuilderM m a b) -> HBuilderM m a (f b)
+joinHBuilderM :: (F.Traversable f, Monad m) => f (HBuilderM m a b) -> HBuilderM m a (f b)
 joinHBuilderM = F.sequenceA
 {-# INLINE     joinHBuilderM #-}
 {-# DEPRECATED joinHBuilderM "Use Data.Traversable.sequenceA instead" #-}
 
 -- | Apply functions to builder
-treeHBuilderM :: (PrimMonad m, F.Traversable f) => f (HBuilderM m a b -> HBuilderM m a' b') -> HBuilderM m a b -> HBuilderM m a' (f b')
+treeHBuilderM :: (Monad m, F.Traversable f) => f (HBuilderM m a b -> HBuilderM m a' b') -> HBuilderM m a b -> HBuilderM m a' (f b')
 treeHBuilderM fs h = F.traverse ($ h) fs
 {-# INLINE     treeHBuilderM #-}
 {-# DEPRECATED treeHBuilderM
diff --git a/histogram-fill.cabal b/histogram-fill.cabal
--- a/histogram-fill.cabal
+++ b/histogram-fill.cabal
@@ -1,5 +1,5 @@
 Name:           histogram-fill
-Version:        0.8.2.0
+Version:        0.8.3.0
 Synopsis:       Library for histograms creation.
 Description:
   This is library for histograms filling. Its aim to provide