diff --git a/Gifcurry.cabal b/Gifcurry.cabal
--- a/Gifcurry.cabal
+++ b/Gifcurry.cabal
@@ -1,5 +1,5 @@
 name:                Gifcurry
-version:             2.0.0.0
+version:             2.0.0.1
 synopsis:            Create animated GIFs, overlaid with optional text, from video files.
 description:         GIF creation utility.
 homepage:            https://github.com/lettier/gifcurry
@@ -21,12 +21,12 @@
 
 library
   exposed-modules: Gifcurry
-  build-depends: base >=4.7 && <4.9, process >=1.2 && <1.3, temporary >=1.2 && <1.3, directory ==1.2.*
+  build-depends: base >=4.7 && <=4.9.0.0, process >=1.2 && <=1.4.2.0, temporary >=1.2 && <1.3, directory ==1.2.*
   default-language: Haskell2010
 
 executable gifcurry_gui
   main-is:             Main.hs
-  build-depends:       base >=4.7 && <4.9, gtk3 >=0.14 && <0.15, process >=1.2 && <1.3, temporary >=1.2 && <1.3, directory ==1.2.*
+  build-depends:       base >=4.7 && <=4.9.0.0, gtk3 >=0.14 && <0.15, process >=1.2 && <=1.4.2.0, temporary >=1.2 && <1.3, directory ==1.2.*
   other-modules:       Paths_Gifcurry, Gifcurry
   ghc-options:         -O3 -threaded -with-rtsopts=-N
   hs-source-dirs:      gui_src, ./
@@ -34,7 +34,7 @@
 
 executable gifcurry_cli
   main-is:             Main.hs
-  build-depends:       base >=4.7 && <4.9, process >=1.2 && <1.3, temporary >=1.2 && <1.3, directory == 1.2.*, cmdargs ==0.10.*
+  build-depends:       base >=4.7 && <=4.9.0.0, process >=1.2 && <=1.4.2.0, temporary >=1.2 && <1.3, directory == 1.2.*, cmdargs ==0.10.*
   other-modules:       Gifcurry
   hs-source-dirs:      cli_src, ./
   default-language:    Haskell2010
diff --git a/Gifcurry.hs b/Gifcurry.hs
--- a/Gifcurry.hs
+++ b/Gifcurry.hs
@@ -21,14 +21,14 @@
 
 -- | The data type record required by 'gif'.
 data GifParams = GifParams {
-      inputFile :: [Char]
-    , outputFile :: [Char]
+      inputFile :: String
+    , outputFile :: String
     , startTime :: Float
     , durationTime :: Float
     , widthSize :: Int
     , qualityPercent :: Float
-    , topText :: [Char]
-    , bottomText :: [Char]
+    , topText :: String
+    , bottomText :: String
   } deriving (Show, Read)
 
 -- | Specifies default parameters for 'startTime', 'durationTime', 'widthSize', and 'qualityPercent'.
@@ -107,7 +107,7 @@
     unless valid $ putStrLn "\n[Error] Invalid params."
     return valid
 
-printGifParams :: GifParams -> [Char] -> IO ()
+printGifParams :: GifParams -> String -> IO ()
 printGifParams
   GifParams {
       inputFile = ipf
@@ -131,7 +131,7 @@
       , "\nWriting temporary frames to... " ++ tmpdir
     ]
 
-tryFfmpeg :: GifParams -> [Char] -> IO (Either IOError String)
+tryFfmpeg :: GifParams -> String -> IO (Either IOError String)
 tryFfmpeg
   GifParams {
       inputFile = ipf
@@ -166,7 +166,7 @@
         dts = printf "%.3f" dt
         wss = show ws
 
-tryConvert :: GifParams -> [Char] -> IO (Either IOError String)
+tryConvert :: GifParams -> String -> IO (Either IOError String)
 tryConvert
   GifParams {
       outputFile = opf
@@ -210,7 +210,7 @@
   | otherwise  = truncate (qpc / 100.0 * 256.0)
   where qpc = qualityPercentClamp qp
 
-annotate :: Int -> [Char] -> [Char] -> [[Char]]
+annotate :: Int -> String -> String -> [String]
 annotate widthSize text topBottom = [
       "-gravity"
     , topBottom
@@ -235,7 +235,7 @@
   ]
   where ps = show $ pointSize widthSize text
 
-pointSize :: Int -> [Char] -> Int
+pointSize :: Int -> String -> Int
 pointsize _ "" = 0
 pointSize widthSize text
   | widthSize <= 0  = 0
diff --git a/README.md b/README.md
--- a/README.md
+++ b/README.md
@@ -53,11 +53,13 @@
 ## Dependencies
 
 * [Haskell](https://www.haskell.org/platform/)
+  * [alex](https://hackage.haskell.org/package/alex)
+  * [happy](https://hackage.haskell.org/package/happy)
+  * [gtk2hs-buildtools](https://hackage.haskell.org/package/gtk2hs-buildtools)
+  * [cmdargs](https://hackage.haskell.org/package/cmdargs)
   * [System.IO.Temp (temporary)](https://hackage.haskell.org/package/temporary)
   * [Graphics.UI.Gtk (gtk)](https://hackage.haskell.org/package/gtk3)
   * [System.Directory (directory)](https://hackage.haskell.org/package/directory)
-  * [gtk2hs-buildtools](https://hackage.haskell.org/package/gtk2hs-buildtools)
-  * [cmdargs](https://hackage.haskell.org/package/cmdargs)
 * [FFmpeg](https://www.ffmpeg.org/download.html)
 * [ImageMagick](http://www.imagemagick.org/script/download.php)
 * [GTK+](http://www.gtk.org/download/index.php)
@@ -151,6 +153,7 @@
 # Install ffmpeg and imagemagick
 cabal update
 cabal configure
+cabal install alex happy -j
 cabal install gtk2hs-buildtools -j
 cabal install gifcurry -j
 cd ~/.cabal/bin
@@ -168,6 +171,7 @@
 cabal sandbox init
 cabal update
 cabal configure
+cabal install alex happy -j
 cabal install gtk2hs-buildtools -j
 cabal install -j
 ./.cabal-sandbox/bin/gifcurry_gui
diff --git a/cli_src/Main.hs b/cli_src/Main.hs
--- a/cli_src/Main.hs
+++ b/cli_src/Main.hs
@@ -14,14 +14,14 @@
 import qualified Gifcurry (gif, GifParams(..), defaultGifParams, gifParamsValid)
 
 data CliArgs = CliArgs {
-      inputFile :: [Char]
-    , outputFile :: [Char]
+      inputFile :: String
+    , outputFile :: String
     , startTime :: Float
     , durationTime :: Float
     , widthSize :: Int
     , qualityPercent :: Float
-    , topText :: [Char]
-    , bottomText :: [Char]
+    , topText :: String
+    , bottomText :: String
   } deriving (Data, Typeable, Show, Eq)
 
 cliargs = CliArgs {
diff --git a/gui_src/Main.hs b/gui_src/Main.hs
--- a/gui_src/Main.hs
+++ b/gui_src/Main.hs
@@ -83,13 +83,13 @@
     if paramsValid
       then do
         forkOS $ do
-          entrySetText statusEntry "One GIF coming up!"
+          postGUIAsync $ entrySetText statusEntry "One GIF coming up!"
           success <- (ioSuccess . gif) params
           if not success
-            then entrySetText statusEntry "Did not work. Check your settings."
+            then postGUIAsync $ entrySetText statusEntry "Did not work. Check your settings."
             else do
               forkOS $ openGifCommand outputFilePathName
-              entrySetText statusEntry "Ready."
+              postGUIAsync $ entrySetText statusEntry "Ready."
         return ()
       else entrySetText statusEntry "Settings are wrong."
     return ()
@@ -130,7 +130,7 @@
   builderAddFromFile builder gladeFile
   return builder
 
-inputFileButtonGetText :: FileChooserButton -> IO [Char]
+inputFileButtonGetText :: FileChooserButton -> IO String
 inputFileButtonGetText inputFileButton = do
   inputFileButtonText <- fileChooserGetFilename inputFileButton
   inputFilePathName <- case inputFileButtonText of
@@ -146,7 +146,7 @@
     Nothing -> return nothing
     Just x -> return x
 
-assembleOutputFilePathName :: FileChooserButton -> Entry -> IO ([Char], [Char])
+assembleOutputFilePathName :: FileChooserButton -> Entry -> IO (String, String)
 assembleOutputFilePathName outputFilePathButton outputFileNameEntry = do
   outputFilePathText <- fileChooserGetFilename outputFilePathButton
   outputFilePath <- case outputFilePathText of
@@ -157,18 +157,18 @@
   let outputFilePathName = outputFilePath ++ "/" ++ outputGifFileName
   return (outputGifFileName, outputFilePathName)
 
-openGifCommand :: [Char] -> IO ()
+openGifCommand :: String -> IO ()
 openGifCommand outputFilePathName = do
   fileExists <- doesFileExist outputFilePathName
   when fileExists $ do
     spawnCommand $ command ++ outputFilePathName
     return ()
-  where command = if "linux" `isInfixOf` (fmap toLower System.Info.os) then "xdg-open " else "open "
+  where command = if "linux" `isInfixOf` fmap toLower System.Info.os then "xdg-open " else "open "
 
 resetImage :: Image -> IO ()
 resetImage image = imageSetFromIconName image "gtk-missing-image" IconSizeButton
 
-makeGifPreview :: [Char] -> [Char] -> Float -> [Char] -> IO (Either IOError String)
+makeGifPreview :: String -> String -> Float -> String -> IO (Either IOError String)
 makeGifPreview inputFile outputFile startTime bottomText = gif $ defaultGifParams {
       inputFile = inputFile
     , outputFile = outputFile
@@ -198,9 +198,9 @@
         let outputFilePathName = tmpdir ++ "/end.gif"
         success <- ioSuccess $ makeGifPreview inputFilePathName outputFilePathName startTime' " LAST FRAME  "
         if success
-          then imageSetFromFile lastFrameImage outputFilePathName
-          else resetImage lastFrameImage
-      else resetImage lastFrameImage
+          then postGUIAsync $ imageSetFromFile lastFrameImage outputFilePathName
+          else postGUIAsync $ resetImage lastFrameImage
+      else postGUIAsync $ resetImage lastFrameImage
   return ()
 
 makeFirstFramePreview :: FileChooserButton -> Entry -> Entry -> Image -> Image -> IO ()
@@ -209,12 +209,12 @@
     withTempDirectory "." "previews" $ \tmpDir -> do
       inputFilePathName <- inputFileButtonGetText inputFileButton
       startTime <- entryGetFloat startTimeEntry (-1.0)
-      if (not $ null inputFilePathName) && (startTime >= 0.0) then do
+      if not (null inputFilePathName) && (startTime >= 0.0) then do
         let outputFilePathName = tmpDir ++ "/start.gif"
         success <- ioSuccess $ makeGifPreview inputFilePathName outputFilePathName startTime " FIRST FRAME "
         if success
-          then imageSetFromFile firstFrameImage outputFilePathName
-          else resetImage firstFrameImage
-      else resetImage firstFrameImage
+          then postGUIAsync $ imageSetFromFile firstFrameImage outputFilePathName
+          else postGUIAsync $ resetImage firstFrameImage
+      else postGUIAsync $ resetImage firstFrameImage
     makeLastFramePreview inputFileButton startTimeEntry durationTimeEntry lastFrameImage
   return ()