diff --git a/hierarchical-clustering.cabal b/hierarchical-clustering.cabal
--- a/hierarchical-clustering.cabal
+++ b/hierarchical-clustering.cabal
@@ -1,5 +1,5 @@
 Name:                hierarchical-clustering
-Version:             0.4.4
+Version:             0.4.5
 Synopsis:            Fast algorithms for single, average/UPGMA and complete linkage clustering.
 License:             BSD3
 License-file:        LICENSE
@@ -26,10 +26,6 @@
   @Data.Clustering.Hierarchical@ automatically chooses the best
   implementation we have.
   .
-  Changes in version 0.4.4:
-  .
-  * Remove most upper bounds.
-  .
   Changes in version 0.4:
   .
   * Specialize the distance type to Double for efficiency reasons.
@@ -79,7 +75,7 @@
 
 Source-repository head
   type: darcs
-  location: http://patch-tag.com/r/felipe/hierarchical-clustering
+  location: https://github.com/meteficha/hierarchical-clustering
 
 
 Library
@@ -91,8 +87,8 @@
     Data.Clustering.Hierarchical.Internal.Types
   Build-depends:
       base       == 4.*
-    , array      >= 0.3
-    , containers >= 0.3
+    , array      >= 0.3 && < 0.6
+    , containers >= 0.3 && < 0.6
   GHC-options: -Wall
 
 Test-suite runtests
@@ -102,7 +98,7 @@
   Build-depends:
       base       == 4.*
 
-    , hspec      >= 0.9
+    , hspec      >= 2.1
     , HUnit      >= 1.2
     , QuickCheck >= 2.4
 
diff --git a/src/Data/Clustering/Hierarchical/Internal/DistanceMatrix.hs b/src/Data/Clustering/Hierarchical/Internal/DistanceMatrix.hs
--- a/src/Data/Clustering/Hierarchical/Internal/DistanceMatrix.hs
+++ b/src/Data/Clustering/Hierarchical/Internal/DistanceMatrix.hs
@@ -1,4 +1,4 @@
-{-# LANGUAGE BangPatterns #-}
+{-# LANGUAGE BangPatterns, FlexibleContexts #-}
 
 module Data.Clustering.Hierarchical.Internal.DistanceMatrix
     (singleLinkage
diff --git a/src/Data/Clustering/Hierarchical/Internal/Optimal.hs b/src/Data/Clustering/Hierarchical/Internal/Optimal.hs
--- a/src/Data/Clustering/Hierarchical/Internal/Optimal.hs
+++ b/src/Data/Clustering/Hierarchical/Internal/Optimal.hs
@@ -1,4 +1,4 @@
-{-# LANGUAGE BangPatterns #-}
+{-# LANGUAGE BangPatterns, FlexibleContexts #-}
 
 -- | Implementations that are optimal in space and time.
 module Data.Clustering.Hierarchical.Internal.Optimal
diff --git a/tests/runtests.hs b/tests/runtests.hs
--- a/tests/runtests.hs
+++ b/tests/runtests.hs
@@ -8,12 +8,11 @@
 import Text.Show.Functions ()
 
 -- from hspec
-import Test.Hspec.Monadic (hspecX, describe, it, pending, Specs)
-import Test.Hspec.HUnit ()
+import Test.Hspec (hspec, describe, it, pendingWith, shouldBe, Spec)
 import Test.Hspec.QuickCheck (prop)
 
 -- from HUnit
-import Test.HUnit ((~?=), Assertion, assertFailure)
+import Test.HUnit (Assertion, assertFailure)
 
 -- from QuickCheck
 import Test.QuickCheck (Property, Arbitrary(..), Gen, forAll)
@@ -25,11 +24,11 @@
 
 
 main :: IO ()
-main = hspecX $ do
+main = hspec $ do
          test_cutAt
          test_dendrogram
 
-test_cutAt :: Specs
+test_cutAt :: Spec
 test_cutAt =
     describe "cutAt" $ do
       let dendro      :: Dendrogram Char
@@ -43,7 +42,7 @@
 
       let testFor threshold expected =
               it (printf "works for 'dendro' with threshold %0.1f" threshold) $
-                 dendro `cutAt` threshold ~?= expected
+                 dendro `cutAt` threshold `shouldBe` expected
 
       testFor 0.9 [dendro]
       testFor 0.8 [dendro]
@@ -53,7 +52,7 @@
       testFor 0.2 [d_0_5_left, d_0_5_right, d_0_8_right]
       testFor 0.1 [d_0_2_left, d_0_2_right, d_0_5_right, d_0_8_right]
 
-test_dendrogram :: Specs
+test_dendrogram :: Spec
 test_dendrogram = do
     describe "Optimal's singleLinkage" $ do
       basicDendrogramTests O.singleLinkage
@@ -88,11 +87,11 @@
                        f1 ps euclideanDist ==== f2 ps euclideanDist
       prop "agree on singleLinkage"   $ test O.singleLinkage DM.singleLinkage
       it "agree on completeLinkage" $
-         pending "This doesn't work because CLINK doesn't \
-                 \always give the best complete linkage."
+         pendingWith "This doesn't work because CLINK doesn't \
+                     \always give the best complete linkage."
 
 
-basicDendrogramTests :: (forall a. [a] -> (a -> a -> Distance) -> Dendrogram a) -> Specs
+basicDendrogramTests :: (forall a. [a] -> (a -> a -> Distance) -> Dendrogram a) -> Spec
 basicDendrogramTests f = do
   it "fails for an empty input" $
      assertErrors (f [] (\_ _ -> zero))