diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,8 @@
+## Version 0.5.1 (2017-12-06)
+
+- Only invoke `setNumCapabilities` when using the `-threaded` runtime ([#130][130], [@ekmett][ekmett])
+- Correct `mixGamma` oddness check ([#124][124], [@markhibberd][markhibberd])
+
 ## Version 0.5 (2017-07-16)
 
 - Parallel state machine testing, allows detection of commands which are not-atomic ([#98][98], [@jystic][jystic])
@@ -58,7 +63,15 @@
   https://github.com/amarpotghan
 [erikd]:
   https://github.com/erikd
+[ekmett]:
+  https://github.com/ekmett
+[markhibberd]:
+  https://github.com/markhibberd
 
+[130]:
+  https://github.com/hedgehogqa/haskell-hedgehog/pull/130
+[124]:
+  https://github.com/hedgehogqa/haskell-hedgehog/pull/124
 [99]:
   https://github.com/hedgehogqa/haskell-hedgehog/pull/99
 [98]:
diff --git a/hedgehog.cabal b/hedgehog.cabal
--- a/hedgehog.cabal
+++ b/hedgehog.cabal
@@ -1,9 +1,7 @@
+version: 0.5.1
+
 name:
   hedgehog
-version:
-  0.5
-license:
-  BSD3
 author:
   Jacob Stanley
 maintainer:
@@ -47,7 +45,7 @@
 library
   build-depends:
       base                            >= 3          && < 5
-    , ansi-terminal                   >= 0.6        && < 0.7
+    , ansi-terminal                   >= 0.6        && < 0.8
     , async                           >= 2.0        && < 2.2
     , bytestring                      >= 0.10       && < 0.11
     , concurrent-output               >= 1.7        && < 1.11
diff --git a/src/Hedgehog/Internal/Config.hs b/src/Hedgehog/Internal/Config.hs
--- a/src/Hedgehog/Internal/Config.hs
+++ b/src/Hedgehog/Internal/Config.hs
@@ -1,3 +1,4 @@
+{-# OPTIONS_HADDOCK not-home #-}
 {-# LANGUAGE CPP #-}
 {-# LANGUAGE DoAndIfThenElse #-}
 {-# LANGUAGE GeneralizedNewtypeDeriving #-}
diff --git a/src/Hedgehog/Internal/Discovery.hs b/src/Hedgehog/Internal/Discovery.hs
--- a/src/Hedgehog/Internal/Discovery.hs
+++ b/src/Hedgehog/Internal/Discovery.hs
@@ -1,3 +1,4 @@
+{-# OPTIONS_HADDOCK not-home #-}
 {-# LANGUAGE DeriveFunctor #-}
 {-# LANGUAGE LambdaCase #-}
 module Hedgehog.Internal.Discovery (
diff --git a/src/Hedgehog/Internal/Distributive.hs b/src/Hedgehog/Internal/Distributive.hs
--- a/src/Hedgehog/Internal/Distributive.hs
+++ b/src/Hedgehog/Internal/Distributive.hs
@@ -1,3 +1,4 @@
+{-# OPTIONS_HADDOCK not-home #-}
 {-# LANGUAGE TypeFamilies #-}
 {-# LANGUAGE KindSignatures #-}
 {-# LANGUAGE TypeOperators #-}
diff --git a/src/Hedgehog/Internal/Exception.hs b/src/Hedgehog/Internal/Exception.hs
--- a/src/Hedgehog/Internal/Exception.hs
+++ b/src/Hedgehog/Internal/Exception.hs
@@ -1,3 +1,4 @@
+{-# OPTIONS_HADDOCK not-home #-}
 module Hedgehog.Internal.Exception (
     tryAll
   , tryEvaluate
diff --git a/src/Hedgehog/Internal/Gen.hs b/src/Hedgehog/Internal/Gen.hs
--- a/src/Hedgehog/Internal/Gen.hs
+++ b/src/Hedgehog/Internal/Gen.hs
@@ -1,3 +1,4 @@
+{-# OPTIONS_HADDOCK not-home #-}
 {-# LANGUAGE DataKinds #-}
 {-# LANGUAGE DeriveFoldable #-}
 {-# LANGUAGE DeriveFunctor #-}
diff --git a/src/Hedgehog/Internal/HTraversable.hs b/src/Hedgehog/Internal/HTraversable.hs
--- a/src/Hedgehog/Internal/HTraversable.hs
+++ b/src/Hedgehog/Internal/HTraversable.hs
@@ -1,3 +1,4 @@
+{-# OPTIONS_HADDOCK not-home #-}
 {-# LANGUAGE RankNTypes #-}
 module Hedgehog.Internal.HTraversable (
     HTraversable(..)
diff --git a/src/Hedgehog/Internal/Opaque.hs b/src/Hedgehog/Internal/Opaque.hs
--- a/src/Hedgehog/Internal/Opaque.hs
+++ b/src/Hedgehog/Internal/Opaque.hs
@@ -1,3 +1,4 @@
+{-# OPTIONS_HADDOCK not-home #-}
 module Hedgehog.Internal.Opaque (
     Opaque(..)
   ) where
diff --git a/src/Hedgehog/Internal/Property.hs b/src/Hedgehog/Internal/Property.hs
--- a/src/Hedgehog/Internal/Property.hs
+++ b/src/Hedgehog/Internal/Property.hs
@@ -1,3 +1,4 @@
+{-# OPTIONS_HADDOCK not-home #-}
 {-# LANGUAGE BangPatterns #-}
 {-# LANGUAGE DeriveFunctor #-}
 {-# LANGUAGE DoAndIfThenElse #-}
diff --git a/src/Hedgehog/Internal/Queue.hs b/src/Hedgehog/Internal/Queue.hs
--- a/src/Hedgehog/Internal/Queue.hs
+++ b/src/Hedgehog/Internal/Queue.hs
@@ -1,3 +1,4 @@
+{-# OPTIONS_HADDOCK not-home #-}
 {-# LANGUAGE GeneralizedNewtypeDeriving #-}
 {-# LANGUAGE LambdaCase #-}
 module Hedgehog.Internal.Queue (
@@ -13,6 +14,7 @@
   , updateNumCapabilities
   ) where
 
+import           Control.Concurrent (rtsSupportsBoundThreads)
 import           Control.Concurrent.Async (forConcurrently)
 import           Control.Concurrent.MVar (MVar)
 import qualified Control.Concurrent.MVar as MVar
@@ -111,6 +113,6 @@
 --   is.
 --
 updateNumCapabilities :: WorkerCount -> IO ()
-updateNumCapabilities (WorkerCount n) = do
+updateNumCapabilities (WorkerCount n) = when rtsSupportsBoundThreads $ do
   ncaps <- Conc.getNumCapabilities
   Conc.setNumCapabilities (max n ncaps)
diff --git a/src/Hedgehog/Internal/Range.hs b/src/Hedgehog/Internal/Range.hs
--- a/src/Hedgehog/Internal/Range.hs
+++ b/src/Hedgehog/Internal/Range.hs
@@ -1,3 +1,4 @@
+{-# OPTIONS_HADDOCK not-home #-}
 {-# LANGUAGE GeneralizedNewtypeDeriving #-}
 module Hedgehog.Internal.Range (
   -- * Size
diff --git a/src/Hedgehog/Internal/Region.hs b/src/Hedgehog/Internal/Region.hs
--- a/src/Hedgehog/Internal/Region.hs
+++ b/src/Hedgehog/Internal/Region.hs
@@ -1,3 +1,4 @@
+{-# OPTIONS_HADDOCK not-home #-}
 module Hedgehog.Internal.Region (
     Region(..)
   , newEmptyRegion
diff --git a/src/Hedgehog/Internal/Report.hs b/src/Hedgehog/Internal/Report.hs
--- a/src/Hedgehog/Internal/Report.hs
+++ b/src/Hedgehog/Internal/Report.hs
@@ -1,3 +1,4 @@
+{-# OPTIONS_HADDOCK not-home #-}
 {-# LANGUAGE DeriveFoldable #-}
 {-# LANGUAGE DeriveFunctor #-}
 {-# LANGUAGE DeriveTraversable #-}
diff --git a/src/Hedgehog/Internal/Runner.hs b/src/Hedgehog/Internal/Runner.hs
--- a/src/Hedgehog/Internal/Runner.hs
+++ b/src/Hedgehog/Internal/Runner.hs
@@ -1,3 +1,4 @@
+{-# OPTIONS_HADDOCK not-home #-}
 {-# LANGUAGE BangPatterns #-}
 {-# LANGUAGE DoAndIfThenElse #-}
 {-# LANGUAGE GeneralizedNewtypeDeriving #-}
diff --git a/src/Hedgehog/Internal/Seed.hs b/src/Hedgehog/Internal/Seed.hs
--- a/src/Hedgehog/Internal/Seed.hs
+++ b/src/Hedgehog/Internal/Seed.hs
@@ -1,3 +1,4 @@
+{-# OPTIONS_HADDOCK not-home #-}
 {-# LANGUAGE CPP #-}
 -- |
 -- This is a port of "Fast Splittable Pseudorandom Number Generators" by Steele
@@ -191,7 +192,7 @@
     y = mix64variant13 x .|. 1
     n = popCount $ y `xor` (y `shiftR` 1)
   in
-    if n < 24 then
+    if n >= 24 then
       y `xor` (-6148914691236517206)
     else
       y
diff --git a/src/Hedgehog/Internal/Show.hs b/src/Hedgehog/Internal/Show.hs
--- a/src/Hedgehog/Internal/Show.hs
+++ b/src/Hedgehog/Internal/Show.hs
@@ -1,3 +1,4 @@
+{-# OPTIONS_HADDOCK not-home #-}
 {-# LANGUAGE LambdaCase #-}
 {-# LANGUAGE PatternGuards #-}
 module Hedgehog.Internal.Show (
diff --git a/src/Hedgehog/Internal/Shrink.hs b/src/Hedgehog/Internal/Shrink.hs
--- a/src/Hedgehog/Internal/Shrink.hs
+++ b/src/Hedgehog/Internal/Shrink.hs
@@ -1,3 +1,4 @@
+{-# OPTIONS_HADDOCK not-home #-}
 module Hedgehog.Internal.Shrink (
     towards
   , towardsFloat
diff --git a/src/Hedgehog/Internal/Source.hs b/src/Hedgehog/Internal/Source.hs
--- a/src/Hedgehog/Internal/Source.hs
+++ b/src/Hedgehog/Internal/Source.hs
@@ -1,3 +1,4 @@
+{-# OPTIONS_HADDOCK not-home #-}
 {-# LANGUAGE ConstraintKinds #-}
 {-# LANGUAGE CPP #-}
 {-# LANGUAGE GeneralizedNewtypeDeriving #-}
diff --git a/src/Hedgehog/Internal/State.hs b/src/Hedgehog/Internal/State.hs
--- a/src/Hedgehog/Internal/State.hs
+++ b/src/Hedgehog/Internal/State.hs
@@ -1,3 +1,4 @@
+{-# OPTIONS_HADDOCK not-home #-}
 {-# LANGUAGE DeriveFoldable #-}
 {-# LANGUAGE DeriveFunctor #-}
 {-# LANGUAGE DeriveTraversable #-}
diff --git a/src/Hedgehog/Internal/TH.hs b/src/Hedgehog/Internal/TH.hs
--- a/src/Hedgehog/Internal/TH.hs
+++ b/src/Hedgehog/Internal/TH.hs
@@ -1,3 +1,4 @@
+{-# OPTIONS_HADDOCK not-home #-}
 {-# LANGUAGE LambdaCase #-}
 {-# LANGUAGE TemplateHaskell #-}
 module Hedgehog.Internal.TH (
diff --git a/src/Hedgehog/Internal/Tree.hs b/src/Hedgehog/Internal/Tree.hs
--- a/src/Hedgehog/Internal/Tree.hs
+++ b/src/Hedgehog/Internal/Tree.hs
@@ -1,3 +1,4 @@
+{-# OPTIONS_HADDOCK not-home #-}
 {-# LANGUAGE CPP #-}
 {-# LANGUAGE FlexibleContexts #-}
 {-# LANGUAGE FlexibleInstances #-}
diff --git a/src/Hedgehog/Internal/Tripping.hs b/src/Hedgehog/Internal/Tripping.hs
--- a/src/Hedgehog/Internal/Tripping.hs
+++ b/src/Hedgehog/Internal/Tripping.hs
@@ -1,3 +1,4 @@
+{-# OPTIONS_HADDOCK not-home #-}
 module Hedgehog.Internal.Tripping (
     tripping
   ) where