diff --git a/creatur.cabal b/creatur.cabal
--- a/creatur.cabal
+++ b/creatur.cabal
@@ -1,5 +1,5 @@
 Name:              creatur
-Version:           5.3.1
+Version:           5.3.2
 Stability:         experimental
 Synopsis:          Framework for artificial life experiments.
 Description:       A software framework for automating experiments
@@ -36,13 +36,12 @@
 source-repository this
   type:     git
   location: https://github.com/mhwombat/creatur.git
-  tag:      5.3.1
+  tag:      5.3.2
 
 library
   GHC-Options:      -Wall -fno-warn-orphans
   Hs-source-dirs:   src
   exposed-modules:  ALife.Creatur,
-                    ALife.Creatur.AgentNamer,
                     ALife.Creatur.Checklist,
                     ALife.Creatur.Clock,
                     ALife.Creatur.Counter,
@@ -60,6 +59,7 @@
                     ALife.Creatur.Genetics.Reproduction.Sexual,
                     ALife.Creatur.Genetics.Reproduction.SimplifiedSexual,
                     ALife.Creatur.Logger,
+                    ALife.Creatur.Namer,
                     ALife.Creatur.Universe,
                     ALife.Creatur.Task,
                     ALife.Creatur.Util
diff --git a/src/ALife/Creatur/AgentNamer.hs b/src/ALife/Creatur/AgentNamer.hs
deleted file mode 100644
--- a/src/ALife/Creatur/AgentNamer.hs
+++ /dev/null
@@ -1,52 +0,0 @@
-------------------------------------------------------------------------
--- |
--- Module      :  ALife.Creatur.AgentNamer
--- Copyright   :  (c) Amy de Buitléir 2012-2013
--- License     :  BSD-style
--- Maintainer  :  amy@nualeargais.ie
--- Stability   :  experimental
--- Portability :  portable
---
--- Assigns a unique ID upon request. IDs generated by an @AgentNamer@ 
--- are guaranteed to be unique within a given universe, across all 
--- simulation runs.
---
-------------------------------------------------------------------------
-module ALife.Creatur.AgentNamer
-  (
-    AgentNamer(..),
-    SimpleAgentNamer,
-    mkSimpleAgentNamer
-  ) where
-
-import ALife.Creatur (AgentId)
-import ALife.Creatur.Counter (PersistentCounter, current, increment,
-  mkPersistentCounter)
-import ALife.Creatur.Util (stateMap)
-import Control.Monad.State (StateT, get, gets)
-
-class AgentNamer n where
-  -- | Assign a unique ID using the supplied prefix.
-  genName :: StateT n IO AgentId
-
-data SimpleAgentNamer = SimpleAgentNamer 
-  {
-    prefix :: String,
-    counter :: PersistentCounter
-  } deriving (Show, Eq)
-
-mkSimpleAgentNamer :: String -> FilePath -> SimpleAgentNamer
-mkSimpleAgentNamer s f = SimpleAgentNamer s $ mkPersistentCounter f
-
-withCounter :: StateT PersistentCounter IO x -> StateT SimpleAgentNamer IO x
-withCounter runProgram = do
-  u <- get
-  stateMap (\c -> u {counter=c}) counter runProgram
-
-instance AgentNamer SimpleAgentNamer where
-  genName = do
-    p <- gets prefix
-    k <- withCounter (increment >> current)
-    return $ p ++ show k
-
-
diff --git a/src/ALife/Creatur/Database/CachedFileSystemInternal.hs b/src/ALife/Creatur/Database/CachedFileSystemInternal.hs
--- a/src/ALife/Creatur/Database/CachedFileSystemInternal.hs
+++ b/src/ALife/Creatur/Database/CachedFileSystemInternal.hs
@@ -12,14 +12,14 @@
 -- This module is subject to change without notice.
 --
 ------------------------------------------------------------------------
-{-# LANGUAGE TypeFamilies, FlexibleContexts #-}
+{-# LANGUAGE TypeFamilies, FlexibleContexts, ScopedTypeVariables #-}
 module ALife.Creatur.Database.CachedFileSystemInternal where
 
 import Prelude hiding (readFile, writeFile, lookup)
 
 import ALife.Creatur.Database (Database(..), DBRecord, Record,
   SizedRecord, delete, key, keys, store, size)
-import ALife.Creatur.Database.FileSystem (FSDatabase, mkFSDatabase)
+import qualified ALife.Creatur.Database.FileSystem as FS
 import ALife.Creatur.Util (stateMap)
 import Control.Monad (when)
 import Control.Monad.State (StateT, get, gets, modify)
@@ -28,7 +28,7 @@
 --   and the name of the file is the record's key.
 data CachedFSDatabase r = CachedFSDatabase
   {
-    database :: FSDatabase r,
+    database :: FS.FSDatabase r,
     cache :: [r],
     maxCacheSize :: Int
   } deriving (Show, Eq)
@@ -59,7 +59,7 @@
 
   store r = do
     addToCache r
-    withFSDB (store r)
+    withFSDB (store r :: StateT (FS.FSDatabase r) IO ())
 
   delete k = do
     deleteByKeyFromCache k
@@ -67,7 +67,7 @@
 
 withFSDB 
   :: Monad m
-    => StateT (FSDatabase r) m a -> StateT (CachedFSDatabase r) m a
+    => StateT (FS.FSDatabase r) m a -> StateT (CachedFSDatabase r) m a
 withFSDB f = do
   d <- get
   stateMap (\x -> d{database=x}) database f
@@ -95,8 +95,8 @@
 deleteFromCache
   :: SizedRecord r
     => r -> StateT (CachedFSDatabase r) IO ()
-deleteFromCache r
-  = modify (\d -> d {cache=filter (\x -> key x /= key r) (cache d)})
+deleteFromCache r =
+  modify (\d -> d {cache=filter (\x -> key x /= key r) (cache d)})
 
 trimCache :: SizedRecord r => StateT (CachedFSDatabase r) IO ()
 trimCache = do
@@ -111,9 +111,10 @@
               else xs
 
 listSize :: SizedRecord r => [r] -> Int
-listSize xs = if null xs then 0 else sum $ map size xs
+listSize [] = 0
+listSize xs = sum $ map size xs
 
 -- | @'mkFSDatabase' d@ (re)creates the FSDatabase in the
 --   directory @d@.
 mkCachedFSDatabase :: FilePath -> Int -> CachedFSDatabase r
-mkCachedFSDatabase d s = CachedFSDatabase (mkFSDatabase d) [] s
+mkCachedFSDatabase d s = CachedFSDatabase (FS.mkFSDatabase d) [] s
diff --git a/src/ALife/Creatur/Namer.hs b/src/ALife/Creatur/Namer.hs
new file mode 100644
--- /dev/null
+++ b/src/ALife/Creatur/Namer.hs
@@ -0,0 +1,51 @@
+------------------------------------------------------------------------
+-- |
+-- Module      :  ALife.Creatur.Namer
+-- Copyright   :  (c) Amy de Buitléir 2012-2013
+-- License     :  BSD-style
+-- Maintainer  :  amy@nualeargais.ie
+-- Stability   :  experimental
+-- Portability :  portable
+--
+-- Assigns a unique ID upon request. IDs generated by an @Namer@ 
+-- are guaranteed to be unique within a given universe, across all 
+-- simulation runs.
+--
+------------------------------------------------------------------------
+module ALife.Creatur.Namer
+  (
+    Namer(..),
+    SimpleNamer,
+    mkSimpleNamer
+  ) where
+
+import ALife.Creatur.Counter (PersistentCounter, current, increment,
+  mkPersistentCounter)
+import ALife.Creatur.Util (stateMap)
+import Control.Monad.State (StateT, get, gets)
+
+class Namer n where
+  -- | Assign a unique ID using the supplied prefix.
+  genName :: StateT n IO String
+
+data SimpleNamer = SimpleNamer 
+  {
+    prefix :: String,
+    counter :: PersistentCounter
+  } deriving (Show, Eq)
+
+mkSimpleNamer :: String -> FilePath -> SimpleNamer
+mkSimpleNamer s f = SimpleNamer s $ mkPersistentCounter f
+
+withCounter :: StateT PersistentCounter IO x -> StateT SimpleNamer IO x
+withCounter runProgram = do
+  u <- get
+  stateMap (\c -> u {counter=c}) counter runProgram
+
+instance Namer SimpleNamer where
+  genName = do
+    p <- gets prefix
+    k <- withCounter (increment >> current)
+    return $ p ++ show k
+
+
diff --git a/src/ALife/Creatur/Universe.hs b/src/ALife/Creatur/Universe.hs
--- a/src/ALife/Creatur/Universe.hs
+++ b/src/ALife/Creatur/Universe.hs
@@ -10,7 +10,7 @@
 -- Provides a habitat for artificial life.
 --
 ------------------------------------------------------------------------
-{-# LANGUAGE TypeFamilies, FlexibleContexts, FlexibleInstances #-}
+{-# LANGUAGE TypeFamilies, FlexibleContexts, FlexibleInstances, ScopedTypeVariables #-}
 module ALife.Creatur.Universe
   (
     -- * Constructors
@@ -51,7 +51,7 @@
 import Prelude hiding (lookup)
 
 import qualified ALife.Creatur as A
-import qualified ALife.Creatur.AgentNamer as N
+import qualified ALife.Creatur.Namer as N
 import qualified ALife.Creatur.Checklist as CL
 import qualified ALife.Creatur.Clock as C
 import qualified ALife.Creatur.Counter as K
@@ -68,7 +68,7 @@
 
 -- | A habitat containing artificial life.
 class (C.Clock (Clock u), L.Logger (Logger u), D.Database (AgentDB u),
-  N.AgentNamer (AgentNamer u), CL.Checklist (Checklist u),
+  N.Namer (Namer u), CL.Checklist (Checklist u),
   A.Agent (Agent u), D.Record (Agent u),
   Agent u ~ D.DBRecord (AgentDB u))
       => Universe u where
@@ -82,9 +82,9 @@
   type AgentDB u
   agentDB :: u -> AgentDB u
   setAgentDB :: u -> AgentDB u -> u
-  type AgentNamer u
-  agentNamer :: u -> AgentNamer u
-  setAgentNamer :: u -> AgentNamer u -> u
+  type Namer u
+  agentNamer :: u -> Namer u
+  setNamer :: u -> Namer u -> u
   type Checklist u
   checklist :: u -> Checklist u
   setChecklist :: u -> Checklist u -> u
@@ -108,12 +108,12 @@
   u <- get
   stateMap (setAgentDB u) agentDB program
 
-withAgentNamer
+withNamer
   :: (Universe u, Monad m)
-    => StateT (AgentNamer u) m a -> StateT u m a
-withAgentNamer program = do
+    => StateT (Namer u) m a -> StateT u m a
+withNamer program = do
   u <- get
-  stateMap (setAgentNamer u) agentNamer program
+  stateMap (setNamer u) agentNamer program
 
 withChecklist
   :: (Universe u, Monad m)
@@ -139,7 +139,7 @@
 
 -- | Generate a unique name for a new agent.
 genName :: Universe u => StateT u IO A.AgentId
-genName = withAgentNamer N.genName
+genName = withNamer N.genName
 
 -- | Returns the list of agents in the population.
 agentIds :: Universe u => StateT u IO [A.AgentId]
@@ -186,9 +186,6 @@
     => Agent u -> StateT u IO ()
 store a = do
   newAgent <- isNew (A.agentId a)
-  -- agentList <- agentIds
-  -- writeToLog $ "DEBUG agents:" ++ show agentList
-  -- writeToLog $ "DEBUG " ++ A.agentId a ++ " new? " ++ show newAgent
   withAgentDB (D.store a) -- Even dead agents should be stored (prior to archiving)
   if A.isAlive a
     then
@@ -200,7 +197,6 @@
       withChecklist $ CL.delete (A.agentId a)
       writeToLog $ (A.agentId a) ++ " archived and removed from lineup"
 
--- | EXPORTED FOR TESTING ONLY
 isNew :: Universe u => A.AgentId -> StateT u IO Bool
 isNew name = fmap (name `notElem`) agentIds
 
@@ -278,12 +274,12 @@
   {
     suClock :: K.PersistentCounter,
     suLogger :: L.SimpleRotatingLogger,
-    suDB :: (FS.FSDatabase a),
-    suNamer :: N.SimpleAgentNamer,
+    suDB :: FS.FSDatabase a,
+    suNamer :: N.SimpleNamer,
     suChecklist :: CL.PersistentChecklist
   } deriving (Show, Eq)
 
-instance (A.Agent a, Serialize a) => Universe (SimpleUniverse a) where
+instance (A.Agent a, D.Record a) => Universe (SimpleUniverse a) where
   type Agent (SimpleUniverse a) = a
   type Clock (SimpleUniverse a) = K.PersistentCounter
   clock = suClock
@@ -294,9 +290,9 @@
   type AgentDB (SimpleUniverse a) = FS.FSDatabase a
   agentDB = suDB
   setAgentDB u d = u { suDB=d }
-  type AgentNamer (SimpleUniverse a) = N.SimpleAgentNamer
+  type Namer (SimpleUniverse a) = N.SimpleNamer
   agentNamer = suNamer
-  setAgentNamer u n = u { suNamer=n }
+  setNamer u n = u { suNamer=n }
   type Checklist (SimpleUniverse a) = CL.PersistentChecklist
   checklist = suChecklist
   setChecklist u cl = u { suChecklist=cl }
@@ -307,20 +303,19 @@
   where c = K.mkPersistentCounter (dir ++ "/clock")
         l = L.mkSimpleRotatingLogger (dir ++ "/log/") name rotateCount
         d = FS.mkFSDatabase (dir ++ "/db")
-        n = N.mkSimpleAgentNamer (name ++ "_") (dir ++ "/namer")
+        n = N.mkSimpleNamer (name ++ "_") (dir ++ "/namer")
         cl = CL.mkPersistentChecklist (dir ++ "/todo")
 
 data CachedUniverse a = CachedUniverse
   {
     cuClock :: K.PersistentCounter,
     cuLogger :: L.SimpleRotatingLogger,
-    cuDB :: (CFS.CachedFSDatabase a),
-    cuNamer :: N.SimpleAgentNamer,
+    cuDB :: CFS.CachedFSDatabase a,
+    cuNamer :: N.SimpleNamer,
     cuChecklist :: CL.PersistentChecklist
   } deriving (Show, Eq)
 
-instance (A.Agent a, Serialize a, D.SizedRecord a)
-    => Universe (CachedUniverse a) where
+instance (A.Agent a, D.SizedRecord a) => Universe (CachedUniverse a) where
   type Agent (CachedUniverse a) = a
   type Clock (CachedUniverse a) = K.PersistentCounter
   clock = cuClock
@@ -331,9 +326,9 @@
   type AgentDB (CachedUniverse a) = CFS.CachedFSDatabase a
   agentDB = cuDB
   setAgentDB u d = u { cuDB=d }
-  type AgentNamer (CachedUniverse a) = N.SimpleAgentNamer
+  type Namer (CachedUniverse a) = N.SimpleNamer
   agentNamer = cuNamer
-  setAgentNamer u n = u { cuNamer=n }
+  setNamer u n = u { cuNamer=n }
   type Checklist (CachedUniverse a) = CL.PersistentChecklist
   checklist = cuChecklist
   setChecklist u cl = u { cuChecklist=cl }
@@ -344,5 +339,5 @@
   where c = K.mkPersistentCounter (dir ++ "/clock")
         l = L.mkSimpleRotatingLogger (dir ++ "/log/") name rotateCount
         d = CFS.mkCachedFSDatabase (dir ++ "/db") cacheSize
-        n = N.mkSimpleAgentNamer (name ++ "_") (dir ++ "/namer")
+        n = N.mkSimpleNamer (name ++ "_") (dir ++ "/namer")
         cl = CL.mkPersistentChecklist (dir ++ "/todo")
diff --git a/test/ALife/Creatur/UtilQC.hs b/test/ALife/Creatur/UtilQC.hs
--- a/test/ALife/Creatur/UtilQC.hs
+++ b/test/ALife/Creatur/UtilQC.hs
@@ -34,8 +34,8 @@
 
 prop_cropRect_returns_correct_size ::
   (Int, Int) -> (Int, Int) -> String -> Int -> Property
-prop_cropRect_returns_correct_size (a,b) (c, d) xs k =
-    property $ length xs' == expectedSize || length xs < expectedSize
+prop_cropRect_returns_correct_size (a,b) (c,d) xs k =
+    property $ length xs' == expectedSize || length xs < minimalOriginalSize
   where expectedSize = length is'
         is = range ((0,0),(lastRow,lastCol))
         is' = filter wanted is
@@ -44,6 +44,9 @@
         lastCol = constrain (-1,length xs - 1) (k - 1)
         delta = if length xs `mod` k == 0 then 0 else 1 --add partial row
         xs' = cropRect (a, b) (c, d) xs k
+        minimalOriginalSize = c*k + d + 1
+          -- the last row of the original matrix must have at least
+          -- d+1 elements
 
 -- Warning: If b < a, returns either a or x
 constrain :: Ord a => (a, a) -> a -> a