diff --git a/src/Broker/PaperBroker.hs b/src/Broker/PaperBroker.hs
index aebc7ee..ee1aac0 100644
--- a/src/Broker/PaperBroker.hs
+++ b/src/Broker/PaperBroker.hs
@@ -10,7 +10,6 @@ module Broker.PaperBroker (
 import Control.DeepSeq
 import Data.Hashable
 import Data.Bits
-import Control.Concurrent.BoundedChan
 import Control.Concurrent.STM
 import Control.Concurrent.STM.TBQueue
 import ATrade.Types
@@ -33,7 +32,6 @@ instance Hashable TickMapKey where
 
 data PaperBrokerState = PaperBrokerState {
   pbTid :: Maybe ThreadId,
-  tickChannel :: TBQueue Tick,
   tickMap :: M.HashMap TickMapKey Tick,
   orders :: M.HashMap OrderId Order,
   cash :: ! Decimal,
@@ -42,16 +40,15 @@ data PaperBrokerState = PaperBrokerState {
 
 mkPaperBroker :: TBQueue Tick -> Decimal -> [T.Text] -> IO BrokerInterface
 mkPaperBroker tickChan startCash accounts = do
-  state <- newIORef PaperBrokerState {
+  state <- atomically $ newTVar PaperBrokerState {
     pbTid = Nothing,
-    tickChannel = tickChan,
     tickMap = M.empty,
     orders = M.empty,
     cash = startCash,
     notificationCallback = Nothing }
 
-  tid <- forkIO $ brokerThread state
-  atomicModifyIORef' state (\s -> (s { pbTid = Just tid }, ()) )
+  tid <- forkIO $ brokerThread tickChan state
+  atomically $ modifyTVar' state (\s -> s { pbTid = Just tid })
 
   return BrokerInterface {
     accounts = accounts,
@@ -60,23 +57,20 @@ mkPaperBroker tickChan startCash accounts = do
     cancelOrder = pbCancelOrder state,
     stopBroker = pbDestroyBroker state }
 
-brokerThread :: IORef PaperBrokerState -> IO ()
-brokerThread state = do
-  chan <- tickChannel <$> readIORef state
-  forever $ do
-    tick <- atomically $ readTBQueue chan
-    atomicModifyIORef' state (\s -> (s { tickMap = M.insert (makeKey tick) tick $! tickMap s }, ()) )
+brokerThread :: TBQueue Tick -> TVar PaperBrokerState -> IO ()
+brokerThread chan state = forever $ atomically $ do
+    tick <- readTBQueue chan
+    modifyTVar' state (\s -> s { tickMap = M.insert (makeKey tick) tick $! tickMap s })
   where
     makeKey !tick = TickMapKey (security $! tick) (datatype tick)
 
-pbSetNotificationCallback :: IORef PaperBrokerState -> Maybe (Notification -> IO ()) -> IO()
-pbSetNotificationCallback state callback = modifyIORef state (\s -> s { notificationCallback = callback } )
+pbSetNotificationCallback :: TVar PaperBrokerState -> Maybe (Notification -> IO ()) -> IO()
+pbSetNotificationCallback state callback = atomically $ modifyTVar' state (\s -> s { notificationCallback = callback } )
 
 
-pbSubmitOrder :: IORef PaperBrokerState -> Order -> IO ()
+pbSubmitOrder :: TVar PaperBrokerState -> Order -> IO ()
 pbSubmitOrder state order = do
   infoM "PaperBroker" $ "Submitted order: " ++ show order
-  curState <- readIORef state
   case orderPrice order of
     Market -> executeMarketOrder state order
     Limit price -> submitLimitOrder state order
@@ -85,14 +79,14 @@ pbSubmitOrder state order = do
 
   where
     executeMarketOrder state order = do
-      tm <- tickMap <$> readIORef state
+      tm <- atomically $ tickMap <$> readTVar state
       case M.lookup key tm of
         Nothing -> let newOrder = order { orderState = OrderError } in
-          atomicModifyIORef' state (\s -> (s { orders = M.insert (orderId order) newOrder $ orders s }, ()) )
+          atomically $ modifyTVar' state (\s -> s { orders = M.insert (orderId order) newOrder $ orders s })
 
         Just tick -> let newOrder = order { orderState = Executed }
                          tradeVolume = (realFracToDecimal 10 (fromIntegral $ orderQuantity order) * value tick) in do
-          atomicModifyIORef' state (\s -> (s { orders = M.insert (orderId order) newOrder $ orders s , cash = cash s - tradeVolume}, ()) )
+          atomically $ modifyTVar' state (\s -> s { orders = M.insert (orderId order) newOrder $ orders s , cash = cash s - tradeVolume})
           debugM "PaperBroker" $ "Executed: " ++ show newOrder
           ts <- getCurrentTime
           maybeCall notificationCallback state $ TradeNotification $ mkTrade tick order ts
@@ -108,7 +102,7 @@ pbSubmitOrder state order = do
 
     key = TickMapKey (orderSecurity order) (orderDatatype order)
     maybeCall proj state arg = do
-      cb <- proj <$> readIORef state
+      cb <- atomically $ proj <$> readTVar state
       case cb of
         Just callback -> callback arg
         Nothing -> return ()
@@ -127,16 +121,16 @@ pbSubmitOrder state order = do
       tradeSignalId = orderSignalId order }
 
 
-pbCancelOrder :: IORef PaperBrokerState -> OrderId -> IO Bool
+pbCancelOrder :: TVar PaperBrokerState -> OrderId -> IO Bool
 pbCancelOrder state order = undefined
 
-pbDestroyBroker :: IORef PaperBrokerState -> IO ()
+pbDestroyBroker :: TVar PaperBrokerState -> IO ()
 pbDestroyBroker state = do
-  maybeTid <- pbTid <$> readIORef state
+  maybeTid <- atomically $ pbTid <$> readTVar state
   case maybeTid of
     Just tid -> killThread tid
     Nothing -> return ()
 
-pbGetOrder :: IORef PaperBrokerState -> OrderId -> IO (Maybe Order)
-pbGetOrder state oid = M.lookup oid . orders <$> readIORef state
+pbGetOrder :: TVar PaperBrokerState -> OrderId -> IO (Maybe Order)
+pbGetOrder state oid = atomically $ M.lookup oid . orders <$> readTVar state