diff --git a/creatur.cabal b/creatur.cabal
--- a/creatur.cabal
+++ b/creatur.cabal
@@ -1,5 +1,5 @@
 Name:              creatur
-Version:           5.9.8.2
+Version:           5.9.9
 Stability:         experimental
 Synopsis:          Framework for artificial life experiments.
 Description:       A software framework for automating experiments
@@ -36,7 +36,7 @@
 source-repository this
   type:     git
   location: https://github.com/mhwombat/creatur.git
-  tag:      5.9.8.2
+  tag:      5.9.9
 
 library
   GHC-Options:      -Wall -fno-warn-orphans
@@ -70,7 +70,7 @@
   Other-modules:    Paths_creatur
   Build-Depends:
                     array ==0.5.*,
-                    base ==4.*,
+                    base ==4.* && >= 4.8,
                     bytestring ==0.10.*,
                     cond ==0.4.*,
                     cereal ==0.4.*,
@@ -98,7 +98,7 @@
   Hs-source-dirs:   test
   Build-Depends:
                     array ==0.5.*,
-                    base ==4.*,
+                    base ==4.* && >= 4.8,
                     binary ==0.7.*,
                     cereal ==0.4.*,
                     creatur,
@@ -135,7 +135,7 @@
 --   GHC-Options:      -Wall
 --   Hs-source-dirs:   test
 --   Build-Depends:
---                     base ==4.*,
+--                     base ==4.* && >= 4.8,
 --                     creatur,
 --                     criterion ==0.8.*,
 --                     test-framework ==0.8.*
diff --git a/src/ALife/Creatur/Genetics/BRGCWord8.hs b/src/ALife/Creatur/Genetics/BRGCWord8.hs
--- a/src/ALife/Creatur/Genetics/BRGCWord8.hs
+++ b/src/ALife/Creatur/Genetics/BRGCWord8.hs
@@ -65,7 +65,7 @@
 import Data.Char (ord, chr)
 import Data.Either (partitionEithers)
 import Data.Functor.Identity (Identity)
-import Data.Word (Word8, Word16)
+import Data.Word (Word8, Word16, Word32, Word64)
 import GHC.Generics
 
 #if MIN_VERSION_base(4,8,0)
@@ -205,18 +205,43 @@
           convert _ = Left "logic error"
 
 instance Genetic Word16 where
-  put g = putAndReport
-            [fromIntegral $ x `div` 0x100, fromIntegral $ x `mod` 0x100]
-              (show g ++ " Word16")
+  put g = putAndReport (integralToBytes 2 x) (show g ++ " Word16")
     where x = integralToGray g
   get = getAndReport 2 grayWord16
 
+instance Genetic Word32 where
+  put g = putAndReport (integralToBytes 4 x) (show g ++ " Word32")
+    where x = integralToGray g
+  get = getAndReport 4 grayWord32
+
+instance Genetic Word64 where
+  put g = putAndReport (integralToBytes 8 x) (show g ++ " Word64")
+    where x = integralToGray g
+  get = getAndReport 8 grayWord64
+
 grayWord16 :: [Word8] -> Either String (Word16, String)
-grayWord16 (x:y:[]) = Right (g, show g ++ " Word16")
-  where g = grayToIntegral (high + low) :: Word16
-        high = fromIntegral x * 0x100
-        low = fromIntegral y
-grayWord16 _ = Left "logic error"
+grayWord16 bs = Right (g, show g ++ " Word16")
+  where g = grayToIntegral . bytesToIntegral $ bs
+
+grayWord32 :: [Word8] -> Either String (Word32, String)
+grayWord32 bs = Right (g, show g ++ " Word32")
+  where g = grayToIntegral . bytesToIntegral $ bs
+
+grayWord64 :: [Word8] -> Either String (Word64, String)
+grayWord64 bs = Right (g, show g ++ " Word64")
+  where g = grayToIntegral . bytesToIntegral $ bs
+
+integralToBytes :: Integral t => Int -> t -> [Word8]
+integralToBytes n x = f n x []
+  where f 0 _ bs = bs
+        f m y bs = f (m-1) y' (b:bs)
+          where y' = y `div` 0x100
+                b = fromIntegral $ y `mod` 0x100
+ 
+bytesToIntegral :: Integral t => [Word8] -> t
+bytesToIntegral bs = f (bs, 0)
+  where f ([], n) = n
+        f (k:ks, n) = f (ks, n*0x100 + fromIntegral k)
 
 instance (Genetic a) => Genetic [a] where
   put xs = do
diff --git a/test/ALife/Creatur/Genetics/BRGCWord8QC.hs b/test/ALife/Creatur/Genetics/BRGCWord8QC.hs
--- a/test/ALife/Creatur/Genetics/BRGCWord8QC.hs
+++ b/test/ALife/Creatur/Genetics/BRGCWord8QC.hs
@@ -22,7 +22,7 @@
 import ALife.Creatur.Genetics.BRGCWord8
 import ALife.Creatur.Genetics.Analysis (Analysable)
 import ALife.Creatur.Util (fromEither)
-import Data.Word (Word8, Word16)
+import Data.Word (Word8, Word16, Word32, Word64)
 import GHC.Generics (Generic)
 import Test.Framework as TF (Test, testGroup)
 import Test.Framework.Providers.QuickCheck2 (testProperty)
@@ -80,6 +80,10 @@
       (prop_round_trippable :: Word8 -> Property),
     testProperty "prop_round_trippable - Word16"
       (prop_round_trippable :: Word16 -> Property),
+    testProperty "prop_round_trippable - Word32"
+      (prop_round_trippable :: Word32 -> Property),
+    testProperty "prop_round_trippable - Word64"
+      (prop_round_trippable :: Word64 -> Property),
     testProperty "prop_round_trippable - TestStructure"
       (prop_round_trippable :: TestStructure -> Property),
     testProperty "prop_rawWord8s_round_trippable"