diff --git a/Data/Weighting/GSC.hs b/Data/Weighting/GSC.hs
--- a/Data/Weighting/GSC.hs
+++ b/Data/Weighting/GSC.hs
@@ -1,7 +1,7 @@
 module Data.Weighting.GSC where
 
 import Data.List (foldl')
-import Data.Clustering.Hierarchical (Dendrogram(..))
+import Data.Clustering.Hierarchical (Dendrogram(..), Distance)
 
 -- | /O(n^2)/ Calculates the Gerstein\/Sonnhammer\/Chothia
 -- weights for all elements of a dendrogram.  Weights are
@@ -41,7 +41,7 @@
 -- @
 --
 -- which is exactly what they calculated.
-gsc :: Fractional d => Dendrogram d a -> Dendrogram d (a, d)
+gsc :: Dendrogram a -> Dendrogram (a, Distance)
 gsc (Leaf x)                  = Leaf (x,1)
 gsc b@(Branch d _ _) | d == 0 = fmap (flip (,) 1) b
 gsc dendrogram                = ret
@@ -78,5 +78,5 @@
                       (nr, r') = setWeights r
                       ns = nl + nr
                   in ns `seq` (ns, Branch d l' r')
-              (nsum, ret) = setWeights b
-          in (0, nsum, ret)
+              (nsum, retz) = setWeights b
+          in (0, nsum, retz)
diff --git a/gsc-weighting.cabal b/gsc-weighting.cabal
--- a/gsc-weighting.cabal
+++ b/gsc-weighting.cabal
@@ -1,5 +1,5 @@
 Name:                gsc-weighting
-Version:             0.1.1.1
+Version:             0.2
 Synopsis:            Generic implementation of Gerstein/Sonnhammer/Chothia weighting.
 License:             BSD3
 License-file:        LICENSE
@@ -22,6 +22,10 @@
   use @UPGMA@ as linkage and residue identity as distance
   function when creating the dendrogram.
   .
+  Changes in version 0.2:
+  .
+  * Updated to work with @hierarchical-clustering@ 0.4.
+  .
   Changes in version 0.1.1.1:
   .
   * Use an stricter upper bound on @hierachical-clustering@.
@@ -42,5 +46,5 @@
     Data.Weighting.GSC
   Build-depends:
       base                    == 4.*
-    , hierarchical-clustering >= 0.1 && < 0.4
+    , hierarchical-clustering == 0.4.*
   GHC-options: -Wall