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: 1.0.0
+version: 1.0.1
 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
@@ -59,6 +59,7 @@
   build-depends:
       attoparsec >= 0.10 && < 0.14
     , base
+    , containers
     , directory
     , filepath
     , ghc-prof
diff --git a/src/GHC/Prof.hs b/src/GHC/Prof.hs
--- a/src/GHC/Prof.hs
+++ b/src/GHC/Prof.hs
@@ -1,12 +1,5 @@
 module GHC.Prof
-  ( Profile(..)
-  , TotalTime(..)
-  , TotalAlloc(..)
-  , AggregateCostCentre(..)
-  , CostCentre(..)
-  , CostCentreNo
-  , Callee(..)
-  , CallSite(..)
+  ( decode
 
   -- * Parser
   , profile
@@ -19,8 +12,27 @@
   , costCentresOrderBy
   , callSites
   , callSitesOrderBy
+
+  -- * Types
+  , Profile(..)
+  , TotalTime(..)
+  , TotalAlloc(..)
+  , AggregateCostCentre(..)
+  , CostCentre(..)
+  , CostCentreNo
+  , Callee(..)
+  , CallSite(..)
   ) where
 
+import qualified Data.Attoparsec.Text.Lazy as ATL
+import qualified Data.Text.Lazy as TL
+
 import GHC.Prof.CostCentreTree
 import GHC.Prof.Parser (profile)
 import GHC.Prof.Types
+
+-- | Decode a GHC time allocation profiling report from a lazy 'ATL.Text'
+decode :: TL.Text -> Either String Profile
+decode text = case ATL.parse profile text of
+  ATL.Fail _unconsumed _contexts reason -> Left reason
+  ATL.Done _unconsumed prof -> Right prof
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
@@ -12,6 +12,7 @@
   , callSites
   , callSitesOrderBy
 
+  , buildAggregateCostCentresOrderBy
   , buildCostCentresOrderBy
   , buildCallSitesOrderBy
   ) where
@@ -24,11 +25,11 @@
 import Data.Traversable (mapM)
 import Prelude hiding (mapM)
 import qualified Data.Foldable as Fold
-import qualified Data.Sequence as Seq
 
-import Data.Sequence (Seq)
+import Data.Set (Set)
 import Data.Text (Text)
 import Data.Tree (Tree)
+import qualified Data.Set as Set
 import qualified Data.Tree as Tree
 
 import GHC.Prof.Types
@@ -41,11 +42,15 @@
 import qualified Data.Map as Map
 #endif
 
+-- | Build a list of cost-centres from a profiling report ordered by the time
+-- spent and the amount of allocation.
 aggregateCostCentres :: Profile -> [AggregateCostCentre]
 aggregateCostCentres = aggregateCostCentresOrderBy sortKey
   where
     sortKey = aggregateCostCentreTime &&& aggregateCostCentreAlloc
 
+-- | Build a list of cost-centres from a profling report ordered by the given
+-- key.
 aggregateCostCentresOrderBy
   :: Ord a
   => (AggregateCostCentre -> a)
@@ -83,7 +88,7 @@
   -> Text
   -- ^ Module name
   -> Profile
-  -> Maybe (Callee, Seq CallSite)
+  -> Maybe (Callee, [CallSite])
 callSites = callSitesOrderBy sortKey
   where
     sortKey =
@@ -102,7 +107,7 @@
   -> Text
   -- ^ Module name
   -> Profile
-  -> Maybe (Callee, Seq CallSite)
+  -> Maybe (Callee, [CallSite])
 callSitesOrderBy sortKey name modName =
   buildCallSitesOrderBy sortKey name modName . profileCostCentreTree
 
@@ -135,7 +140,7 @@
           !children = maybe [] Fold.toList $ do
             nodes <- IntMap.lookup key costCentreChildren
             return $ costCentreNo
-                <$> Seq.unstableSortBy (flip compare `on` sortKey) nodes
+              <$> sortBy (flip compare `on` sortKey) (Set.toList nodes)
 
 buildCallSitesOrderBy
   :: Ord a
@@ -146,7 +151,7 @@
   -> Text
   -- ^ Module name
   -> CostCentreTree
-  -> Maybe (Callee, Seq CallSite)
+  -> Maybe (Callee, [CallSite])
 buildCallSitesOrderBy sortKey name modName tree@CostCentreTree {..} =
   (,) <$> callee <*> callers
   where
@@ -157,17 +162,17 @@
     callers = do
       callees <- lookupCallees
       mapM (buildCallSite tree) $
-        Seq.unstableSortBy (flip compare `on` sortKey) callees
+        sortBy (flip compare `on` sortKey) $ Set.toList callees
 
-buildCallee :: Text -> Text -> Seq CostCentre -> Callee
+buildCallee :: Text -> Text -> Set CostCentre -> Callee
 buildCallee name modName callees = Callee
   { calleeName = name
   , calleeModule = modName
-  , calleeEntries = Fold.sum $ costCentreEntries <$> callees
-  , calleeTime = Fold.sum $ costCentreIndTime <$> callees
-  , calleeAlloc = Fold.sum $ costCentreIndAlloc <$> callees
-  , calleeTicks = asum $ costCentreTicks <$> callees
-  , calleeBytes = asum $ costCentreBytes <$> callees
+  , 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
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
@@ -20,11 +20,10 @@
 import Control.Monad
 import Data.Char (isSpace)
 import Data.Foldable (asum, foldl')
-import Data.Sequence ((><))
 import Data.Maybe
 import Data.Text (Text)
 import Data.Time
-import qualified Data.Sequence as Seq
+import qualified Data.Set as Set
 
 import Data.Attoparsec.Text as A
 
@@ -38,6 +37,7 @@
 import qualified Data.Map as Map
 #endif
 
+-- | Parse a GHC time-allocation profiling report
 profile :: Parser Profile
 profile = do
   skipHorizontalSpace
@@ -51,6 +51,7 @@
   endOfInput
   return $! Profile {..}
 
+-- | Parse the timestamp in a header as local time
 timestamp :: Parser LocalTime
 timestamp = do
   parseDayOfTheWeek >> skipSpace
@@ -264,13 +265,13 @@
             (\parent -> IntMap.insert ccNo parent costCentreParents)
             parentNo
           , costCentreChildren = maybe costCentreChildren
-            (\parent -> IntMap.insertWith (><) parent
-              (Seq.singleton node)
+            (\parent -> IntMap.insertWith Set.union parent
+              (Set.singleton node)
               costCentreChildren)
             parentNo
-          , costCentreCallSites = Map.insertWith (><)
+          , costCentreCallSites = Map.insertWith Set.union
             (costCentreName node, costCentreModule node)
-            (Seq.singleton node)
+            (Set.singleton node)
             costCentreCallSites
           , costCentreAggregate = Map.insertWith addCostCentre
             (costCentreName node, costCentreModule node)
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
@@ -6,7 +6,7 @@
 import Data.IntMap (IntMap)
 import Data.Map (Map)
 import Data.Scientific (Scientific)
-import Data.Sequence (Seq)
+import Data.Set (Set)
 import Data.Text (Text)
 import Data.Time (DiffTime, LocalTime)
 
@@ -55,18 +55,18 @@
   , aggregateCostCentreBytes :: !(Maybe Integer)
   -- ^ Total memory allocation in the cost-centre. This number
   -- exists only if @-P@ or @-Pa@ option is given at run-time.
-  } deriving Show
+  } deriving (Show, Eq, Ord)
 
 -- | Cost-centre node
 data CostCentre = CostCentre
-  { costCentreName :: !Text
+  { costCentreNo :: !CostCentreNo
+  -- ^ Identifier of the cost-centre
+  , costCentreName :: !Text
   -- ^ Name of the cost-centre
   , costCentreModule :: !Text
   -- ^ Module name of the cost-centre
   , costCentreSrc :: !(Maybe Text)
   -- ^ Source location of the cost-centre
-  , costCentreNo :: !CostCentreNo
-  -- ^ Identifier of the cost-centre
   , costCentreEntries :: !Integer
   -- ^ Number of entries to the cost-centre
   , costCentreIndTime :: !Scientific
@@ -81,15 +81,15 @@
   -- ^ Number of ticks in the cost-centre.
   , costCentreBytes :: !(Maybe Integer)
   -- ^ Number of allocated bytes in the cost-centre.
-  } deriving Show
+  } deriving (Show, Eq, Ord)
 
 type CostCentreNo = Int
 
 data CostCentreTree = CostCentreTree
   { costCentreNodes :: !(IntMap CostCentre)
   , costCentreParents :: !(IntMap CostCentreNo)
-  , costCentreChildren :: !(IntMap (Seq CostCentre))
-  , costCentreCallSites :: !(Map (Text, Text) (Seq CostCentre))
+  , costCentreChildren :: !(IntMap (Set CostCentre))
+  , costCentreCallSites :: !(Map (Text, Text) (Set CostCentre))
   , costCentreAggregate :: !(Map (Text, Text) AggregateCostCentre)
   } deriving Show
 
diff --git a/tests/Regression.hs b/tests/Regression.hs
--- a/tests/Regression.hs
+++ b/tests/Regression.hs
@@ -14,8 +14,9 @@
 import System.Process
 import Test.Tasty
 import Test.Tasty.HUnit
-import qualified Data.Text.Lazy.IO as TL
 import qualified Data.Attoparsec.Text.Lazy as ATL
+import qualified Data.Set as Set
+import qualified Data.Text.Lazy.IO as TL
 
 import GHC.Prof
 
@@ -35,7 +36,12 @@
 generateProfiles :: IO [FilePath]
 generateProfiles = do
   withFile "hello.hs" WriteMode $ \h ->
-    hPutStrLn h "main = putStrLn \"Hello, World!\""
+    hPutStrLn h $ unlines
+      [ "import Control.Exception"
+      , "main = evaluate $ fib 100000"
+      , "fib n = fibs !! n"
+      , "fibs = 0:1:zipWith (+) fibs (tail fibs)"
+      ]
   void $ readProcess "ghc" ["-prof", "-rtsopts", "-fforce-recomp", "hello.hs"] ""
   for profilingFlags $ \(name, flag) -> do
     void $ readProcess "./hello" ["+RTS", flag, "-RTS"] ""
@@ -54,7 +60,12 @@
 assertProfile path = do
   text <- TL.readFile path
   case ATL.parse profile text of
-    ATL.Done {} -> return ()
+    ATL.Done _ prof -> do
+      let actual = Set.fromList $ aggregateCostCentres prof
+          expected = Set.fromList $ profileTopCostCentres prof
+      assertBool
+        ("Missing cost centre(s): " ++ show (Set.difference expected actual)) $
+          Set.isSubsetOf expected actual
     ATL.Fail _ _ reason -> assertFailure reason
 
 #if !MIN_VERSION_directory(1, 2, 3)