diff --git a/Data/Weighting/GSC.hs b/Data/Weighting/GSC.hs
--- a/Data/Weighting/GSC.hs
+++ b/Data/Weighting/GSC.hs
@@ -12,18 +12,47 @@
 -- @0@ (in the leafs) and @1@.  The final weights are normalized
 -- to average to @1@ (i.e. sum to the number of sequences, the
 -- same they would sum if all weights were @1@).
+--
+-- For example, suppose we have
+--
+-- @
+-- dendro = Branch 0.8
+--            (Branch 0.5
+--              (Branch 0.2
+--                (Leaf 'A')
+--                (Leaf 'B'))
+--              (Leaf 'C'))
+--            (Leaf 'D')
+-- @
+--
+-- This is the same as GSC paper's example, however they used
+-- similarities while we are using distances (i.e. @fmap (1-)
+-- dendro@ would be exactly their example).  Then @gsc dendro@ is
+--
+-- @
+-- gsc dendro == Branch 0.8
+--                 (Branch 0.5
+--                   (Branch 0.2
+--                     (Leaf ('A',0.7608695652173914))
+--                     (Leaf ('B',0.7608695652173914)))
+--                   (Leaf ('C',1.0869565217391306)))
+--                 (Leaf ('D',1.3913043478260871))
+-- @
+--
+-- which is exactly what they calculated.
 gsc :: Fractional d => Dendrogram d a -> Dendrogram d (a, d)
-gsc (Leaf x) = Leaf (x,1)
-gsc dendro   = let (wsum, nsum, r) = go wfinal undefined [] dendro
-                   wfinal = (wsum / fromIntegral nsum)
-               in r
+gsc (Leaf x)   = Leaf (x,1)
+gsc dendrogram = ret
     where
+      (wsum, nsum, ret) = go undefined [] dendrogram
+      wfinal            = (wsum / fromIntegral nsum)
+
       position (Leaf _)       = 0 -- no difference from itself
       position (Branch d _ _) = d
 
-      go wfinal _ cs (Branch d l r) =
-          let (wl, nl, l') = go wfinal d ((el / wl) : cs) l
-              (wr, nr, r') = go wfinal d ((er / wr) : cs) r
+      go _ cs (Branch d l r) =
+          let (wl, nl, l') = go d ((el / wl) : cs) l
+              (wr, nr, r') = go d ((er / wr) : cs) r
 
               el = d - position l -- edge length to left branch
               er = d - position r --          ...to right branch
@@ -31,7 +60,7 @@
               wsum = wl + wr + el + er
               nsum = nl + nr
           in wsum `seq` nsum `seq` (wsum, nsum, Branch d l' r')
-      go wfinal d cs (Leaf x) =
+      go d cs (Leaf x) =
           -- O(n) worst case, O(log n) best case (balanced dendrogram)
           let w = foldl' (\curw c -> curw + curw * c) d (tail cs)
           in (0, 1 :: Int, Leaf (x, w / wfinal))
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
+Version:             0.1.0.1
 Synopsis:            Generic implementation of Gerstein/Sonnhammer/Chothia weighting.
 License:             BSD3
 License-file:        LICENSE