diff --git a/arbtt.cabal b/arbtt.cabal
--- a/arbtt.cabal
+++ b/arbtt.cabal
@@ -1,5 +1,5 @@
 name:               arbtt
-version:            0.9.0.7
+version:            0.9.0.8
 license:            GPL
 license-file:       LICENSE
 category:           Desktop
@@ -40,9 +40,9 @@
     main-is:            capture-main.hs
     hs-source-dirs:     src
     build-depends:
-        base == 4.5.* || == 4.6.* || == 4.7.* || == 4.8.*,
+        base == 4.7.* || == 4.8.*,
         filepath, directory, transformers, utf8-string,
-        aeson >= 0.6  && < 0.11,
+        aeson >= 0.6  && < 0.12,
         binary >= 0.5,
         bytestring, deepseq
 
@@ -63,6 +63,9 @@
 
     ghc-options: -rtsopts
 
+    if !os(windows)
+        build-depends: unix
+
     if os(windows)
         extra-libraries: psapi
         cpp-options:    -DWIN32
@@ -80,25 +83,28 @@
             Graphics.X11.XScreenSaver
             System.Locale.SetLocale
         build-depends:
-            X11 > 1.4.4, unix
+            X11 > 1.4.4
     default-language: Haskell98
 
 executable arbtt-stats
     main-is:            stats-main.hs
     hs-source-dirs:     src
     build-depends:
-        base == 4.5.* || == 4.6.* || == 4.7.* || == 4.8.*,
+        base == 4.7.* || == 4.8.*,
         parsec == 3.*,
         containers == 0.5.*,
         pcre-light,
         binary >= 0.5,
         deepseq, bytestring, utf8-string, strict,
-        transformers, unix, directory, filepath,
-        aeson >= 0.6  && < 0.11,
+        transformers, directory, filepath,
+        aeson >= 0.6  && < 0.12,
         array == 0.4.* || == 0.5.*,
         terminal-progress-bar,
         bytestring-progress
 
+    if !os(windows)
+        build-depends: unix
+
     if flag(old-locale)
         build-depends: time == 1.4.*, old-locale
     else
@@ -128,15 +134,18 @@
     main-is:            dump-main.hs
     hs-source-dirs:     src
     build-depends:
-        base == 4.5.* || == 4.6.* || == 4.7.* || == 4.8.*,
+        base == 4.7.* || == 4.8.*,
         parsec == 3.*,
         containers == 0.5.*,
-        aeson >= 0.6  && < 0.11,
+        aeson >= 0.6  && < 0.12,
         array == 0.4.* || == 0.5.*,
         binary >= 0.5,
         deepseq, bytestring, utf8-string, strict,
-        transformers, unix, directory, filepath
+        transformers, directory, filepath
 
+    if !os(windows)
+        build-depends: unix
+
     if flag(old-locale)
         build-depends: time == 1.4.*, old-locale
     else
@@ -162,13 +171,16 @@
     main-is:            import-main.hs
     hs-source-dirs:     src
     build-depends:
-        base == 4.5.* || == 4.6.* || == 4.7.* || == 4.8.*,
+        base == 4.7.* || == 4.8.*,
         parsec == 3.*,
         containers == 0.5.*,
         binary >= 0.5,
         deepseq, bytestring, utf8-string, strict,
-        transformers, unix, directory, filepath
+        transformers, directory, filepath
 
+    if !os(windows)
+        build-depends: unix
+
     if flag(old-locale)
         build-depends: time == 1.4.*, old-locale
     else
@@ -192,12 +204,15 @@
     main-is:            recover-main.hs
     hs-source-dirs:     src
     build-depends:
-        base == 4.5.* || == 4.6.* || == 4.7.* || == 4.8.*,
+        base == 4.7.* || == 4.8.*,
         containers == 0.5.*,
         binary >= 0.5,
         deepseq, bytestring, utf8-string,
-        unix, directory, filepath
+        directory, filepath
 
+    if !os(windows)
+        build-depends: unix
+
     if flag(old-locale)
         build-depends: time == 1.4.*, old-locale
     else
@@ -226,7 +241,7 @@
   Main-is:
     test.hs
   Build-depends:
-      base == 4.5.* || == 4.6.* || == 4.7.* || == 4.8.*
+      base == 4.7.* || == 4.8.*
       , tasty >= 0.7 && < 0.12
       , tasty-golden >= 2.2.0.2  && <= 2.4
       , tasty-hunit >= 0.2  && < 0.11
@@ -235,12 +250,14 @@
       , binary >= 0.5
       , bytestring
       , utf8-string
-      , unix
       , directory
       , parsec == 3.*
       , containers == 0.5.*
       , pcre-light
       , transformers
+
+  if !os(windows)
+    build-depends: unix
 
   if flag(old-locale)
         build-depends: time == 1.4.*, old-locale
diff --git a/src/Categorize.hs b/src/Categorize.hs
--- a/src/Categorize.hs
+++ b/src/Categorize.hs
@@ -20,6 +20,7 @@
 import Text.Parsec.Combinator
 import Text.Parsec.Language
 import Text.Parsec.ExprFail
+import System.IO
 import System.Exit
 import Control.Applicative ((<*>),(<$>))
 import Control.DeepSeq
@@ -77,7 +78,9 @@
 
 readCategorizer :: FilePath -> IO Categorizer
 readCategorizer filename = do
-        content <- readFile filename
+        h <- openFile filename ReadMode
+        hSetEncoding h utf8
+        content <- hGetContents h
         time <- getCurrentTime
         tz <- getCurrentTimeZone
         case flip runReader tz $
diff --git a/src/Graphics/Win32/Window/Extra.hsc b/src/Graphics/Win32/Window/Extra.hsc
--- a/src/Graphics/Win32/Window/Extra.hsc
+++ b/src/Graphics/Win32/Window/Extra.hsc
@@ -11,6 +11,8 @@
 import System.Win32.Process
 import System.Win32.File    ( closeHandle )
 import System.IO
+import Control.Exception  (tryJust)
+import System.IO.Error (isPermissionError)
 import Control.Exception    ( bracket )
 import Control.Monad
 
@@ -67,12 +69,15 @@
         t <- (#peek LASTINPUTINFO, dwTime) buf
         return $ LASTINPUTINFO t
 
+ignoreEPerm = tryJust (guard . isPermissionError)
+
 fetchWindowTitles :: IO [(HWND, String,String)]
 fetchWindowTitles = do
 	resultRef <- newIORef []
-	callback <- mkEnumWindowsProc $ \winh _ -> do
+	callback <- mkEnumWindowsProc $ \winh _ ->
+	 do ignoreEPerm $ do
                 v <- c_IsWindowVisible winh -- only consider visible windows
-                if not v then return True else do
+                when v $ do
                 proc <- alloca $ \pid_p -> do
                         c_GetWindowThreadProcessId winh pid_p 
                         pid <- peek pid_p
@@ -97,7 +102,7 @@
 			 else peekTString c_test
                 unless (str `elem` ["", "Default IME"]) $ do -- Ignore some windows by default
                         modifyIORef resultRef ((winh,str,proc):)
-                return True
+            return True
 	c_EnumWindows callback 0
 	readIORef resultRef
 
diff --git a/src/LeftFold.hs b/src/LeftFold.hs
--- a/src/LeftFold.hs
+++ b/src/LeftFold.hs
@@ -73,13 +73,13 @@
 runOnGroups eq _ (Pure ox) = Pure ox
 runOnGroups eq (Pure ix) (LeftFold sto po fo) = LeftFold (S.Nothing :!: sto) go finish 
     where go (S.Nothing :!: so) x             = (S.Just x :!: so)
-          go (S.Just x' :!: so) x | x `eq` x' = (S.Just x :!: so)
+          go (S.Just x' :!: so) x | x' `eq` x = (S.Just x :!: so)
                                   | otherwise = (S.Just x :!: po so ix)
           finish (S.Nothing :!: so) = fo so
           finish (S.Just _  :!: so) = fo (po so ix)
 runOnGroups eq (LeftFold sti pi fi) (LeftFold sto po fo) = LeftFold (S.Nothing :!: sti :!: sto) go finish 
     where go (S.Nothing :!: si :!: so) x             = (S.Just x :!: pi si x  :!: so)
-          go (S.Just x' :!: si :!: so) x | x `eq` x' = (S.Just x :!: pi si x  :!: so)
+          go (S.Just x' :!: si :!: so) x | x' `eq` x = (S.Just x :!: pi si x  :!: so)
                                          | otherwise = (S.Just x :!: pi sti x :!: po so (fi si))
           finish (S.Nothing :!: si :!: so) = fo so
           finish (S.Just _  :!: si :!: so) = fo (po so (fi si))
diff --git a/src/Stats.hs b/src/Stats.hs
--- a/src/Stats.hs
+++ b/src/Stats.hs
@@ -36,6 +36,7 @@
 import qualified Data.Strict as Strict
 import Data.Traversable (sequenceA)
 import Control.Arrow
+import Debug.Trace
 
 import Data
 import Categorize
@@ -323,22 +324,28 @@
                 else []
                 )
 
+tlRateTimediff :: TimeLogEntry a -> NominalDiffTime
+tlRateTimediff tle = fromIntegral (tlRate tle) / 1000
+
 processIntervalReport :: ReportOptions -> String -> (ActivityData -> Maybe String) -> LeftFold (Bool :!: TimeLogEntry (Ctx, ActivityData)) ReportResults
 processIntervalReport opts title extr = runOnIntervals  go1 go2
   where
     go1 :: LeftFold (TimeLogEntry (Ctx, ActivityData)) [Interval]
     go1 = go3 `mapElems` fmap (extr . snd) 
     go3 :: LeftFold (TimeLogEntry (Maybe String)) [Interval]
-    go3 = runOnGroups ((==) `on` tlData) go4 (onJusts toList)
+    go3 = runOnGroups sameGroup go4 (onJusts toList)
+    sameGroup tl1 tl2 =
+        tlData tl1 == tlData tl2
+         && tlTime tl2 `diffUTCTime` tlTime tl1 < 2 * tlRateTimediff tl1
     go4 :: LeftFold (TimeLogEntry (Maybe String)) (Maybe Interval)
     go4 = pure (\fe le ->
         case tlData fe of
             Just str -> Just
                 ( str
                 , showUtcTime (tlTime fe)
-                , showUtcTime (tlTime le)
+                , showUtcTime (tlRateTimediff le `addUTCTime` tlTime le)
                 , showTimeDiff opts $
-                    tlTime le `diffUTCTime` tlTime fe + fromIntegral (tlRate fe)/1000
+                    tlTime le `diffUTCTime` tlTime fe + tlRateTimediff le
                 )
             Nothing -> Nothing) <*>
         (fromJust <$> lfFirst) <*>
diff --git a/src/TermSize.hsc b/src/TermSize.hsc
--- a/src/TermSize.hsc
+++ b/src/TermSize.hsc
@@ -1,4 +1,4 @@
-{-# LANGUAGE ForeignFunctionInterface #-}
+{-# LANGUAGE ForeignFunctionInterface, CPP #-}
 
 {-
 By hammar on http://stackoverflow.com/a/12807521/946226
diff --git a/src/TimeLog.hs b/src/TimeLog.hs
--- a/src/TimeLog.hs
+++ b/src/TimeLog.hs
@@ -1,3 +1,4 @@
+{-# LANGUAGE CPP #-}
 module TimeLog where
 
 import Data
@@ -16,7 +17,9 @@
 import Control.Exception
 import Prelude hiding (catch)
 import Control.DeepSeq
+#ifndef mingw32_HOST_OS
 import System.Posix.Files
+#endif
 import System.IO.Unsafe (unsafeInterleaveIO)
 
 import qualified Data.ByteString.Lazy as BS
@@ -38,7 +41,9 @@
         tle <- mkTimeLogEntry delay entry
 
         createTimeLog False filename
+#ifndef mingw32_HOST_OS
         setFileMode filename (ownerReadMode `unionFileModes` ownerWriteMode)
+#endif
         appendTimeLog filename prev tle
         threadDelay (fromIntegral delay * 1000)
         loop (Just entry)
diff --git a/src/stats-main.hs b/src/stats-main.hs
--- a/src/stats-main.hs
+++ b/src/stats-main.hs
@@ -14,7 +14,6 @@
 import Control.Applicative
 import qualified Data.ByteString.Lazy as BS
 import Data.ByteString.Lazy.Progress
-import System.Posix.Files
 import System.ProgressBar
 import TermSize
 import qualified Data.MyText as T
@@ -178,13 +177,14 @@
      exitFailure
   categorizer <- readCategorizer (optCategorizeFile flags)
 
-  timelog <- BS.readFile (optLogFile flags)
+  timeloghandle <- openBinaryFile (optLogFile flags) ReadMode
+  size <- hFileSize timeloghandle
+  timelog <- BS.hGetContents timeloghandle
   isTerm <- hIsTerminalDevice stderr
 
   trackedTimelog <- case isTerm of
     True -> do
       hSetBuffering stderr NoBuffering
-      size <- fileSize <$> getFileStatus (optLogFile flags)
       trackProgressWithChunkSize (fromIntegral size `div` 100) (\_ b -> do
         (_height, width) <- getTermSize
         hPutChar stderr '\r'
diff --git a/tests/gap-handling.cfg b/tests/gap-handling.cfg
new file mode 100644
--- /dev/null
+++ b/tests/gap-handling.cfg
@@ -0,0 +1,1 @@
+tag Program:$current.program
diff --git a/tests/gap-handling.log b/tests/gap-handling.log
new file mode 100644
Binary files /dev/null and b/tests/gap-handling.log differ
diff --git a/tests/gap-handling.out b/tests/gap-handling.out
new file mode 100644
--- /dev/null
+++ b/tests/gap-handling.out
@@ -0,0 +1,11 @@
+Intervals for category "Program"
+================================
+__________________Tag_|______________From_|_____________Until_|_Duration_
+gnome-terminal-server | 09/20/15 14:24:03 | 09/20/15 14:25:22 |    1m19s
+            Navigator | 09/20/15 14:25:22 | 09/20/15 14:26:22 |    1m00s
+            Navigator | 09/20/15 14:49:31 | 09/20/15 14:55:41 |    6m10s
+gnome-terminal-server | 09/20/15 14:55:41 | 09/20/15 14:56:31 |      50s
+gnome-terminal-server | 09/20/15 18:51:47 | 09/20/15 18:52:17 |      30s
+            Navigator | 09/20/15 18:52:17 | 09/20/15 18:52:37 |      20s
+            Navigator | 09/20/15 18:53:15 | 09/20/15 18:53:55 |      40s
+gnome-terminal-server | 09/20/15 18:53:55 | 09/20/15 18:54:25 |      30s
diff --git a/tests/test.hs b/tests/test.hs
--- a/tests/test.hs
+++ b/tests/test.hs
@@ -10,7 +10,7 @@
 import Control.Exception
 import Data.Typeable
 import System.Exit
-import System.Posix.Env
+import System.Environment
 
 import Categorize
 import TimeLog
@@ -18,7 +18,7 @@
 import Data.Time.Clock
 
 main = do
-    putEnv "TZ=UTC" -- to make tests reproducible
+    setEnv "TZ" "UTC" -- to make tests reproducible
     defaultMain tests
 
 tests :: TestTree
@@ -71,6 +71,9 @@
     , goldenVsString "stats small unicode"
         "tests/unicode_stats.out" $
         run "dist/build/arbtt-stats/arbtt-stats" ["--logfile", "tests/unicode.log", "--categorize", "tests/unicode.cfg"] B.empty
+    , goldenVsString "stats gap handling"
+        "tests/gap-handling.out" $
+        run "dist/build/arbtt-stats/arbtt-stats" ["--logfile", "tests/gap-handling.log", "--categorize", "tests/gap-handling.cfg", "--intervals", "Program:"] B.empty
     ]
 
 
@@ -79,7 +82,7 @@
    (ex,stdout,stderr) <- readProcessWithExitCode cmd args stdin
    unless (B.null stderr) $ throwIO $ StderrException stderr
    case ex of
-     ExitSuccess   -> return stdout
+     ExitSuccess   -> return (B.filter (not . (==13)) stdout) -- windows compat
      ExitFailure r -> throwIO $ ExitCodeException r
 
 data StderrException = StderrException B.ByteString