diff --git a/bin/dump.hs b/bin/dump.hs
--- a/bin/dump.hs
+++ b/bin/dump.hs
@@ -9,7 +9,6 @@
 
 import Data.Scientific
 import Data.Tree (drawTree)
-import qualified Data.Attoparsec.Text.Lazy as ATL
 import qualified Data.Text as T
 import qualified Data.Text.Lazy.IO as TLIO
 
@@ -19,10 +18,9 @@
 main = do
   (opts, file:restArgs) <- parseOpts =<< getArgs
   text <- TLIO.readFile file
-  case ATL.parse profile text of
-    ATL.Fail unconsumed contexts reason ->
-      fail $ show (unconsumed, contexts, reason)
-    ATL.Done _ prof -> case optMode opts of
+  case decode text of
+    Left reason -> fail reason
+    Right prof -> case optMode opts of
       AggregateMode ->
         traverse_ (putStrLn . makeAggregateCCName) $ aggregateCostCentres prof
       TreeMode -> case restArgs of
diff --git a/ghc-prof.cabal b/ghc-prof.cabal
--- a/ghc-prof.cabal
+++ b/ghc-prof.cabal
@@ -1,5 +1,5 @@
 name: ghc-prof
-version: 1.0.1
+version: 1.1.0
 synopsis: Library for parsing GHC time and allocation profiling reports
 description: Library for parsing GHC time and allocation profiling reports
 homepage: https://github.com/maoe/ghc-prof
@@ -23,6 +23,8 @@
     GHC.Prof.Parser
     GHC.Prof.Types
     GHC.Prof.CostCentreTree
+  other-modules:
+    Control.Monad.Extras
   build-depends:
       base == 4.*
     , attoparsec < 0.14
@@ -44,7 +46,6 @@
   hs-source-dirs: bin
   build-depends:
       base
-    , attoparsec
     , containers
     , ghc-prof
     , scientific < 0.4
diff --git a/src/Control/Monad/Extras.hs b/src/Control/Monad/Extras.hs
new file mode 100644
--- /dev/null
+++ b/src/Control/Monad/Extras.hs
@@ -0,0 +1,6 @@
+module Control.Monad.Extras (seqM) where
+
+seqM :: Monad m => m a -> m a
+seqM m = do
+  a <- m
+  return $! a
diff --git a/src/GHC/Prof.hs b/src/GHC/Prof.hs
--- a/src/GHC/Prof.hs
+++ b/src/GHC/Prof.hs
@@ -20,7 +20,6 @@
   , AggregateCostCentre(..)
   , CostCentre(..)
   , CostCentreNo
-  , Callee(..)
   , CallSite(..)
   ) where
 
diff --git a/src/GHC/Prof/CostCentreTree.hs b/src/GHC/Prof/CostCentreTree.hs
--- a/src/GHC/Prof/CostCentreTree.hs
+++ b/src/GHC/Prof/CostCentreTree.hs
@@ -1,7 +1,7 @@
 {-# LANGUAGE BangPatterns #-}
 {-# LANGUAGE CPP #-}
 {-# LANGUAGE RecordWildCards #-}
-{-# OPTIONS_GHC -fsimpl-tick-factor=115 #-}
+{-# OPTIONS_GHC -fsimpl-tick-factor=200 #-}
 module GHC.Prof.CostCentreTree
   ( aggregateCostCentres
   , aggregateCostCentresOrderBy
@@ -18,7 +18,6 @@
   ) where
 import Control.Applicative
 import Control.Arrow ((&&&))
-import Data.Foldable (asum)
 import Data.Function (on)
 import Data.List
 import Data.Maybe (listToMaybe)
@@ -26,7 +25,6 @@
 import Prelude hiding (mapM)
 import qualified Data.Foldable as Fold
 
-import Data.Set (Set)
 import Data.Text (Text)
 import Data.Tree (Tree)
 import qualified Data.Set as Set
@@ -88,7 +86,7 @@
   -> Text
   -- ^ Module name
   -> Profile
-  -> Maybe (Callee, [CallSite])
+  -> Maybe (AggregateCostCentre, [CallSite])
 callSites = callSitesOrderBy sortKey
   where
     sortKey =
@@ -107,7 +105,7 @@
   -> Text
   -- ^ Module name
   -> Profile
-  -> Maybe (Callee, [CallSite])
+  -> Maybe (AggregateCostCentre, [CallSite])
 callSitesOrderBy sortKey name modName =
   buildCallSitesOrderBy sortKey name modName . profileCostCentreTree
 
@@ -151,29 +149,16 @@
   -> Text
   -- ^ Module name
   -> CostCentreTree
-  -> Maybe (Callee, [CallSite])
+  -> Maybe (AggregateCostCentre, [CallSite])
 buildCallSitesOrderBy sortKey name modName tree@CostCentreTree {..} =
   (,) <$> callee <*> callers
   where
     lookupCallees = Map.lookup (name, modName) costCentreCallSites
-    !callee = do
-      callees <- lookupCallees
-      return $ buildCallee name modName callees
+    callee = Map.lookup (name, modName) costCentreAggregate
     callers = do
       callees <- lookupCallees
       mapM (buildCallSite tree) $
         sortBy (flip compare `on` sortKey) $ Set.toList callees
-
-buildCallee :: Text -> Text -> Set CostCentre -> Callee
-buildCallee name modName callees = Callee
-  { calleeName = name
-  , calleeModule = modName
-  , calleeEntries = Fold.sum $ Set.map costCentreEntries callees
-  , calleeTime = Fold.sum $ Set.map costCentreIndTime callees
-  , calleeAlloc = Fold.sum $ Set.map costCentreIndAlloc callees
-  , calleeTicks = asum $ Set.map costCentreTicks callees
-  , calleeBytes = asum $ Set.map costCentreBytes callees
-  }
 
 buildCallSite :: CostCentreTree -> CostCentre -> Maybe CallSite
 buildCallSite CostCentreTree {..} CostCentre {..} = do
diff --git a/src/GHC/Prof/Parser.hs b/src/GHC/Prof/Parser.hs
--- a/src/GHC/Prof/Parser.hs
+++ b/src/GHC/Prof/Parser.hs
@@ -27,6 +27,7 @@
 
 import Data.Attoparsec.Text as A
 
+import Control.Monad.Extras (seqM)
 import GHC.Prof.Types
 
 #if MIN_VERSION_containers(0, 5, 0)
@@ -93,8 +94,8 @@
   void $ string " secs"; skipSpace
   (ticks, resolution, processors) <- parens $ (,,)
     <$> decimal <* string " ticks @ "
-    <*> picoSeconds <* string ", "
-    <*> decimal <* many1 (notChar ')')
+    <*> picoSeconds
+    <*> optional (string ", " *> decimal <* many1 (notChar ')'))
   return $! TotalTime
     { totalTimeElapsed = elapsed
     , totalTimeTicks = ticks
@@ -158,6 +159,7 @@
   <$> symbol <* skipHorizontalSpace -- name
   <*> symbol <* skipHorizontalSpace -- module
   <*> source <* skipHorizontalSpace -- src
+  <*> pure Nothing -- entries
   <*> scientific <* skipHorizontalSpace -- %time
   <*> scientific <* skipHorizontalSpace -- %alloc
   <*> optional decimal <* skipHorizontalSpace -- ticks
@@ -279,6 +281,7 @@
               { aggregateCostCentreName = costCentreName node
               , aggregateCostCentreModule = costCentreModule node
               , aggregateCostCentreSrc = costCentreSrc node
+              , aggregateCostCentreEntries = Just $! costCentreEntries node
               , aggregateCostCentreTime = costCentreIndTime node
               , aggregateCostCentreAlloc = costCentreIndAlloc node
               , aggregateCostCentreTicks = costCentreTicks node
@@ -287,14 +290,17 @@
             costCentreAggregate
           }
         addCostCentre x y = x
-          { aggregateCostCentreTime =
+          { aggregateCostCentreEntries = seqM $ (+)
+            <$> aggregateCostCentreEntries x
+            <*> aggregateCostCentreEntries y
+          , aggregateCostCentreTime =
             aggregateCostCentreTime x + aggregateCostCentreTime y
           , aggregateCostCentreAlloc =
             aggregateCostCentreAlloc x + aggregateCostCentreAlloc y
-          , aggregateCostCentreTicks = (+)
+          , aggregateCostCentreTicks = seqM $ (+)
             <$> aggregateCostCentreTicks x
             <*> aggregateCostCentreTicks y
-          , aggregateCostCentreBytes = (+)
+          , aggregateCostCentreBytes = seqM $ (+)
             <$> aggregateCostCentreBytes x
             <*> aggregateCostCentreBytes y
           }
diff --git a/src/GHC/Prof/Types.hs b/src/GHC/Prof/Types.hs
--- a/src/GHC/Prof/Types.hs
+++ b/src/GHC/Prof/Types.hs
@@ -28,7 +28,7 @@
   -- ^ Total number of ticks
   , totalTimeResolution :: !DiffTime
   -- ^ Duration of a tick
-  , totalTimeProcessors :: !Int
+  , totalTimeProcessors :: !(Maybe Int)
   -- ^ Number of processors
   } deriving Show
 
@@ -45,6 +45,8 @@
   -- ^ Module name of the cost-centre
   , aggregateCostCentreSrc :: !(Maybe Text)
   -- ^ Source location of the cost-centre
+  , aggregateCostCentreEntries :: !(Maybe Integer)
+  -- ^ Number of entries to the cost-centre
   , aggregateCostCentreTime :: !Scientific
   -- ^ Total time spent in the cost-centre
   , aggregateCostCentreAlloc :: !Scientific
@@ -101,23 +103,6 @@
   , costCentreCallSites = mempty
   , costCentreAggregate = mempty
   }
-
-data Callee = Callee
-  { calleeName :: Text
-  -- ^ Name of the callee function
-  , calleeModule :: Text
-  -- ^ Module name of the calle function
-  , calleeEntries :: !Integer
-  -- ^ Number of entries to the callee function
-  , calleeTime :: !Scientific
-  -- ^ Time spent in the callee function
-  , calleeAlloc :: !Scientific
-  -- ^ Allocation incurred by the callee function
-  , calleeTicks :: !(Maybe Integer)
-  -- ^ Number of ticks in the callee function
-  , calleeBytes :: !(Maybe Integer)
-  -- ^ Number of allocated bytes in the callee function
-  } deriving Show
 
 data CallSite = CallSite
   { callSiteCostCentre :: CostCentre
diff --git a/tests/Regression.hs b/tests/Regression.hs
--- a/tests/Regression.hs
+++ b/tests/Regression.hs
@@ -1,10 +1,11 @@
 {-# LANGUAGE CPP #-}
 {-# LANGUAGE ViewPatterns #-}
 module Main where
-import Data.Foldable
-import Data.Traversable
 import Control.Applicative
 import Control.Monad
+import Data.Foldable
+import Data.Monoid
+import Data.Traversable
 import System.Directory
 import System.FilePath
 import System.IO
@@ -61,12 +62,36 @@
   text <- TL.readFile path
   case ATL.parse profile text of
     ATL.Done _ prof -> do
-      let actual = Set.fromList $ aggregateCostCentres prof
-          expected = Set.fromList $ profileTopCostCentres prof
+      let actual = Set.fromList $ map Similar $ aggregateCostCentres prof
+          expected = Set.fromList $ map Similar $ profileTopCostCentres prof
       assertBool
         ("Missing cost centre(s): " ++ show (Set.difference expected actual)) $
           Set.isSubsetOf expected actual
     ATL.Fail _ _ reason -> assertFailure reason
+
+newtype Similar = Similar AggregateCostCentre
+
+instance Show Similar where
+  show (Similar a) = show a
+
+instance Eq Similar where
+  Similar a == Similar b =
+    aggregateCostCentreName a == aggregateCostCentreName b
+    && aggregateCostCentreModule a == aggregateCostCentreModule b
+    && aggregateCostCentreTime a == aggregateCostCentreTime b
+    && aggregateCostCentreAlloc a == aggregateCostCentreAlloc b
+    && aggregateCostCentreTicks a == aggregateCostCentreTicks b
+    && aggregateCostCentreBytes a == aggregateCostCentreBytes b
+
+
+instance Ord Similar where
+  compare (Similar a) (Similar b) =
+    compare (aggregateCostCentreName a) (aggregateCostCentreName b)
+    <> compare (aggregateCostCentreModule a) (aggregateCostCentreModule b)
+    <> compare (aggregateCostCentreTime a) (aggregateCostCentreTime b)
+    <> compare (aggregateCostCentreAlloc a) (aggregateCostCentreAlloc b)
+    <> compare (aggregateCostCentreTicks a) (aggregateCostCentreTicks b)
+    <> compare (aggregateCostCentreBytes a) (aggregateCostCentreBytes b)
 
 #if !MIN_VERSION_directory(1, 2, 3)
 withCurrentDirectory :: FilePath -> IO a -> IO a