diff --git a/pandoc-plantuml-diagrams.cabal b/pandoc-plantuml-diagrams.cabal
--- a/pandoc-plantuml-diagrams.cabal
+++ b/pandoc-plantuml-diagrams.cabal
@@ -1,5 +1,5 @@
 name:                pandoc-plantuml-diagrams
-version:             0.1.0.4
+version:             0.1.1.0
 synopsis:            Render and insert PlantUML diagrams with Pandoc
 description:         PlantUML renders different types of UML diagrams.
                      This filter invokes plantuml.jar (which must be present
@@ -32,6 +32,7 @@
                      , directory
                      , utf8-string
                      , bytestring
+                     , text
   hs-source-dirs:      src
   default-language:    Haskell2010
 
@@ -68,6 +69,7 @@
                      , bytestring
                      , process
                      , directory
+                     , text
 
 source-repository head
   type:                git
diff --git a/src/Text/Pandoc/PlantUML/Filter.hs b/src/Text/Pandoc/PlantUML/Filter.hs
--- a/src/Text/Pandoc/PlantUML/Filter.hs
+++ b/src/Text/Pandoc/PlantUML/Filter.hs
@@ -1,3 +1,4 @@
+{-# LANGUAGE OverloadedStrings #-}
 
 -- |
 -- Module    : Text.Pandoc.PlantUML.Filter
@@ -8,6 +9,7 @@
 
 import Text.Pandoc.JSON
 import Control.Monad
+import qualified Data.Text as T
 
 import Text.Pandoc.PlantUML.Filter.Types
 import Text.Pandoc.PlantUML.Filter.FileNameGenerator
diff --git a/src/Text/Pandoc/PlantUML/Filter/FileNameGenerator.hs b/src/Text/Pandoc/PlantUML/Filter/FileNameGenerator.hs
--- a/src/Text/Pandoc/PlantUML/Filter/FileNameGenerator.hs
+++ b/src/Text/Pandoc/PlantUML/Filter/FileNameGenerator.hs
@@ -14,13 +14,15 @@
 
 import Data.Digest.Pure.SHA (sha1, showDigest)
 import Data.ByteString.Lazy.UTF8 (fromString)
+import qualified Data.Text as T
 
 import Text.Pandoc.PlantUML.Filter.Types
 
 -- | Generates the Hash of a diagram source, and prefixes that.
 fileNameForSource :: DiagramSource -> ImageName
 fileNameForSource (DiagramSource source) = prefix ++ (hash source)
-  where hash = showDigest . sha1 . fromString
+  where
+    hash = showDigest . sha1 . fromString . T.unpack
 
 -- | The prefix to put before rendered images
 prefix :: String
diff --git a/src/Text/Pandoc/PlantUML/Filter/Formats.hs b/src/Text/Pandoc/PlantUML/Filter/Formats.hs
--- a/src/Text/Pandoc/PlantUML/Filter/Formats.hs
+++ b/src/Text/Pandoc/PlantUML/Filter/Formats.hs
@@ -1,3 +1,4 @@
+{-# LANGUAGE OverloadedStrings #-}
 
 -- | Module : Text.Pandoc.PlantUML.Filter.Formats
 -- Determines the image type to be used for one particular
@@ -10,6 +11,7 @@
 
 import Text.Pandoc.Definition
 import Text.Pandoc.PlantUML.Filter.Types
+import qualified Data.Text as T
 
 -- | The image file type to be used for the given output format.
 -- EPS is used for latex outputs, as it provides lossless scalability
diff --git a/src/Text/Pandoc/PlantUML/Filter/IORender.hs b/src/Text/Pandoc/PlantUML/Filter/IORender.hs
--- a/src/Text/Pandoc/PlantUML/Filter/IORender.hs
+++ b/src/Text/Pandoc/PlantUML/Filter/IORender.hs
@@ -7,13 +7,15 @@
 import Data.ByteString.Lazy (hGetContents, hPut)
 import System.Process
 import System.Directory
+import qualified Data.Text.IO as T
+import qualified Data.Text    as T
 
 import Text.Pandoc.PlantUML.Filter.Types
 
 instance ImageIO IO where
   renderImage imageFileName (DiagramSource source) = do
     (Just hIn, Just hOut, _, _) <- createProcess $ plantUmlProcess imageFileName
-    hPutStr hIn source
+    T.hPutStr hIn source
     hClose hIn
     withImageFile $ pipe hOut
     hClose hOut
@@ -21,7 +23,7 @@
   doesImageExist imageFileName = doesFileExist $ show imageFileName
 
 plantUmlProcess :: ImageFileName -> CreateProcess
-plantUmlProcess (ImageFileName _ fileType) = (proc "java" ["-jar", "plantuml.jar", "-pipe", "-t" ++ fileType])
+plantUmlProcess (ImageFileName _ fileType) = (proc "java" ["-jar", "plantuml.jar", "-pipe", "-t" <> T.unpack fileType])
   { std_in = CreatePipe, std_out = CreatePipe }
 
 pipe :: Handle -> Handle -> IO ()
diff --git a/src/Text/Pandoc/PlantUML/Filter/OutputBlock.hs b/src/Text/Pandoc/PlantUML/Filter/OutputBlock.hs
--- a/src/Text/Pandoc/PlantUML/Filter/OutputBlock.hs
+++ b/src/Text/Pandoc/PlantUML/Filter/OutputBlock.hs
@@ -1,4 +1,4 @@
-
+{-# LANGUAGE OverloadedStrings #-}
 -- | Module : Text.Pandoc.PlantUML.Filter.OutputBlock
 -- Renders an image file name and some attributes into a Pandoc
 -- block, like so:
@@ -13,16 +13,17 @@
 import Text.Pandoc.JSON
 import Text.Pandoc.PlantUML.Filter.Types
 import Data.Maybe
+import qualified Data.Text as T
 
 -- | The result block, as specified in the module header.
 resultBlock :: ImageFileName -> Attr -> Block
 resultBlock imageFileName attr = Para $ map (\p -> p imageFileName attr) [imageTag, idTag]
 
 imageTag :: ImageFileName -> Attr -> Inline
-imageTag imageFileName attr    = Image nullAttr (altTagInline attr) (show imageFileName, "fig:")
+imageTag imageFileName attr    = Image nullAttr (altTagInline attr) (T.pack $ show imageFileName, "fig:")
 
 idTag :: ImageFileName -> Attr -> Inline
-idTag _ (id, _, _)             = Str ("{#" ++ id ++ "}")
+idTag _ (id, _, _)             = Str ("{#" <> id <> "}")
 
 altTagInline :: Attr -> [Inline]
 altTagInline (_, _, keyValues)
diff --git a/src/Text/Pandoc/PlantUML/Filter/Types.hs b/src/Text/Pandoc/PlantUML/Filter/Types.hs
--- a/src/Text/Pandoc/PlantUML/Filter/Types.hs
+++ b/src/Text/Pandoc/PlantUML/Filter/Types.hs
@@ -7,14 +7,17 @@
 --
 module Text.Pandoc.PlantUML.Filter.Types where
 
+import           Data.Text(Text)
+import qualified Data.Text as T
+
 -- | The name of an image, without extension, usually a hash
 type ImageName = String
 
 -- | The source of a diagram
-newtype DiagramSource = DiagramSource String deriving (Eq, Show)
+newtype DiagramSource = DiagramSource Text deriving (Eq, Show)
 
 -- | An image format, e.g. "eps"
-type ImageFormat = String
+type ImageFormat = Text
 
 -- | A filename of an image. It contains the basename (myawesomepicture) and
 -- the extension (jpg). It can be shown, which is basically
@@ -24,7 +27,7 @@
 -- | Show the image file name by joining basename and extension with
 -- a dot, yielding picture.jpg
 instance Show ImageFileName where
-  show (ImageFileName name format) = name ++ "." ++ format
+  show (ImageFileName name format) = name <> "." <> T.unpack format
 
 -- | External impure actions are encapsulated in this monad.
 class Monad m => ImageIO m where
diff --git a/test/Text/Pandoc/PlantUML/Filter/FileNameGeneratorSpec.hs b/test/Text/Pandoc/PlantUML/Filter/FileNameGeneratorSpec.hs
--- a/test/Text/Pandoc/PlantUML/Filter/FileNameGeneratorSpec.hs
+++ b/test/Text/Pandoc/PlantUML/Filter/FileNameGeneratorSpec.hs
@@ -1,4 +1,4 @@
-
+{-# LANGUAGE OverloadedStrings #-}
 
 module Text.Pandoc.PlantUML.Filter.FileNameGeneratorSpec where
 
diff --git a/test/Text/Pandoc/PlantUML/Filter/FormatsSpec.hs b/test/Text/Pandoc/PlantUML/Filter/FormatsSpec.hs
--- a/test/Text/Pandoc/PlantUML/Filter/FormatsSpec.hs
+++ b/test/Text/Pandoc/PlantUML/Filter/FormatsSpec.hs
@@ -1,15 +1,16 @@
-
+{-# LANGUAGE OverloadedStrings #-}
 
 module Text.Pandoc.PlantUML.Filter.FormatsSpec where
 
 import Test.Hspec
 import Text.Pandoc.Definition
 import Text.Pandoc.PlantUML.Filter.Formats
+import Data.Text
 
-formatFor :: String -> String
+formatFor :: Text -> Text
 formatFor = imageFormatTypeFor . Format
 
-shouldBeFormattedAs :: String -> String -> Expectation
+shouldBeFormattedAs :: Text -> Text -> Expectation
 shouldBeFormattedAs docFormat imageFormat = (imageFormatTypeFor (Format docFormat)) `shouldBe` imageFormat
 
 spec :: Spec
diff --git a/test/Text/Pandoc/PlantUML/Filter/OutputBlockSpec.hs b/test/Text/Pandoc/PlantUML/Filter/OutputBlockSpec.hs
--- a/test/Text/Pandoc/PlantUML/Filter/OutputBlockSpec.hs
+++ b/test/Text/Pandoc/PlantUML/Filter/OutputBlockSpec.hs
@@ -1,3 +1,4 @@
+{-# LANGUAGE OverloadedStrings #-}
 
 module Text.Pandoc.PlantUML.Filter.OutputBlockSpec where
 
diff --git a/test/Text/Pandoc/PlantUML/Filter/TypesSpec.hs b/test/Text/Pandoc/PlantUML/Filter/TypesSpec.hs
--- a/test/Text/Pandoc/PlantUML/Filter/TypesSpec.hs
+++ b/test/Text/Pandoc/PlantUML/Filter/TypesSpec.hs
@@ -1,3 +1,4 @@
+{-# LANGUAGE OverloadedStrings #-}
 
 module Text.Pandoc.PlantUML.Filter.TypesSpec where
 
diff --git a/test/Text/Pandoc/PlantUML/FilterSpec.hs b/test/Text/Pandoc/PlantUML/FilterSpec.hs
--- a/test/Text/Pandoc/PlantUML/FilterSpec.hs
+++ b/test/Text/Pandoc/PlantUML/FilterSpec.hs
@@ -1,4 +1,5 @@
 {-# LANGUAGE FlexibleInstances #-}
+{-# LANGUAGE OverloadedStrings #-}
 
 module Text.Pandoc.PlantUML.FilterSpec where
 
@@ -9,6 +10,7 @@
 import Text.Pandoc.PlantUML.Filter.FileNameGenerator
 import Text.Pandoc.PlantUML.Filter
 import Control.Monad.State.Lazy as S
+import Data.Text
 
 type FakeImageIO = S.State WorldInfo
 
@@ -32,7 +34,7 @@
     S.put st { renderedImages = ((show fileName), source) : oldImages}
 
 
-runProcessingIn :: WorldInfo -> String -> Block -> (Block, WorldInfo)
+runProcessingIn :: WorldInfo -> Text -> Block -> (Block, WorldInfo)
 runProcessingIn wi format block = S.runState (processBlocks (Just (Format format)) block) wi