diff --git a/CHANGES b/CHANGES
--- a/CHANGES
+++ b/CHANGES
@@ -25,3 +25,6 @@
 
 0.2.0.3:
 		added mutual_information to Numeric.Statistics.Shannon
+
+0.2.0.4:
+		fixed definition of mutual_information
diff --git a/hstatistics.cabal b/hstatistics.cabal
--- a/hstatistics.cabal
+++ b/hstatistics.cabal
@@ -1,5 +1,5 @@
 Name:               hstatistics
-Version:            0.2.0.3
+Version:            0.2.0.4
 License:            GPL
 License-file:       LICENSE
 Copyright:          (c) A.V.H. McPhail 2010
@@ -22,7 +22,7 @@
 library
 
     Build-Depends:      base >= 3 && < 5,
-                        hmatrix >= 0.9.3, hmatrix-gsl-stats >= 0.1.0.2
+                        hmatrix >= 0.9.3, hmatrix-gsl-stats >= 0.1.1.3
 
     Extensions:         
 
diff --git a/lib/Numeric/Statistics/Shannon.hs b/lib/Numeric/Statistics/Shannon.hs
--- a/lib/Numeric/Statistics/Shannon.hs
+++ b/lib/Numeric/Statistics/Shannon.hs
@@ -27,16 +27,14 @@
 import Numeric.LinearAlgebra.Algorithms
 import Numeric.LinearAlgebra.Interface()
 
-import Prelude hiding (sum)
-
-sum x = dot x (constant 1.0 (dim x))
+--import Prelude hiding (sum)
 
 -- | the entropy \sum p_i l\ln{p_i} of a sequence
 entropy :: H.Histogram             -- the underlying distribution
         -> Vector Double         -- the sequence (expected to fall within bounds of Histogram)
         -> Double                -- the entropy
 entropy p x = let ps = H.prob p x
-              in sum (ps * log ps) 
+              in dot ps (log ps)
 
 -- | the mutuaal information \sum_x \sum_y \ln{\frac{p(x,y)}{p(x)p(y)}}
 mutual_information :: H2.Histogram2D -- the underlying distribution
@@ -47,4 +45,4 @@
 mutual_information p px py z@(x,y) = let ps = H2.prob p z
                                          xs = H.prob px x
                                          ys = H.prob py y
-                               in sum $ log (ps/(xs*ys)) 
+                               in dot ps (log (ps/(xs*ys)))