4 files changed, 13 insertions, 7 deletions
diff --git a/src/Text/Pandoc/Lua/Marshaling/ReaderOptions.hs b/src/Text/Pandoc/Lua/Marshaling/ReaderOptions.hs
index 226fe2e71..e8860c92c 100644
--- a/src/Text/Pandoc/Lua/Marshaling/ReaderOptions.hs
+++ b/src/Text/Pandoc/Lua/Marshaling/ReaderOptions.hs
@@ -1,6 +1,7 @@
 {-# LANGUAGE NoImplicitPrelude    #-}
 {-# LANGUAGE FlexibleInstances    #-}
 {-# LANGUAGE ScopedTypeVariables  #-}
+{-# LANGUAGE OverloadedStrings    #-}
 {-# LANGUAGE LambdaCase           #-}
 {-# OPTIONS_GHC -fno-warn-orphans #-}
 {- |
@@ -67,7 +68,8 @@ instance Pushable ReaderOptions where
         indexReaderOptions _tbl (AnyValue key) = do
           Lua.ltype key >>= \case
             Lua.TypeString -> Lua.peek key >>= \case
-              "defaultImageExtension" -> Lua.push defaultImageExtension
+              ("defaultImageExtension" :: Text.Text)
+                                    -> Lua.push defaultImageExtension
               "indentedCodeClasses" -> Lua.push indentedCodeClasses
               "stripComments" -> Lua.push stripComments
               "tabStop" -> Lua.push tabStop
diff --git a/src/Text/Pandoc/Lua/Marshaling/Version.hs b/src/Text/Pandoc/Lua/Marshaling/Version.hs
index f1d4bfd7f..9f80952fb 100644
--- a/src/Text/Pandoc/Lua/Marshaling/Version.hs
+++ b/src/Text/Pandoc/Lua/Marshaling/Version.hs
@@ -1,6 +1,7 @@
 {-# OPTIONS_GHC -fno-warn-orphans #-}
 {-# LANGUAGE LambdaCase           #-}
 {-# LANGUAGE NoImplicitPrelude    #-}
+{-# LANGUAGE OverloadedStrings    #-}
 {- |
    Module      : Text.Pandoc.Lua.Marshaling.Version
    Copyright   : © 2019 Albert Krewinkel
@@ -19,6 +20,7 @@ module Text.Pandoc.Lua.Marshaling.Version
   where
 
 import Prelude
+import Data.Text (Text)
 import Data.Maybe (fromMaybe)
 import Data.Version (Version (..), makeVersion, parseVersion, showVersion)
 import Foreign.Lua (Lua, Optional (..), NumResults,
@@ -103,7 +105,7 @@ __index v (AnyValue k) = do
       Lua.push (Lua.Optional versionPart)
       return 1
     Lua.TypeString -> do
-      str <- Lua.peek k
+      (str :: Text) <- Lua.peek k
       if str == "must_be_at_least"
         then 1 <$ Lua.pushHaskellFunction must_be_at_least
         else 1 <$ Lua.pushnil
diff --git a/src/Text/Pandoc/Lua/Module/MediaBag.hs b/src/Text/Pandoc/Lua/Module/MediaBag.hs
index 951571ddd..2e354ba02 100644
--- a/src/Text/Pandoc/Lua/Module/MediaBag.hs
+++ b/src/Text/Pandoc/Lua/Module/MediaBag.hs
@@ -1,4 +1,5 @@
 {-# LANGUAGE NoImplicitPrelude #-}
+{-# LANGUAGE OverloadedStrings #-}
 {- |
    Module      : Text.Pandoc.Lua.Module.MediaBag
    Copyright   : Copyright © 2017-2019 Albert Krewinkel
@@ -108,9 +109,9 @@ mediaDirectoryFn = do
   addEntry :: Lua.Integer -> (FilePath, MimeType, Int) -> Lua ()
   addEntry idx (fp, mimeType, contentLength) = do
     Lua.newtable
-    Lua.push "path" *> Lua.push fp *> Lua.rawset (-3)
-    Lua.push "type" *> Lua.push mimeType *> Lua.rawset (-3)
-    Lua.push "length" *> Lua.push contentLength *> Lua.rawset (-3)
+    Lua.push ("path" :: T.Text) *> Lua.push fp *> Lua.rawset (-3)
+    Lua.push ("type" :: T.Text) *> Lua.push mimeType *> Lua.rawset (-3)
+    Lua.push ("length" :: T.Text) *> Lua.push contentLength *> Lua.rawset (-3)
     Lua.rawseti (-2) idx
 
 fetch :: T.Text
diff --git a/src/Text/Pandoc/Lua/Util.hs b/src/Text/Pandoc/Lua/Util.hs
index e55bc3495..9c5da1088 100644
--- a/src/Text/Pandoc/Lua/Util.hs
+++ b/src/Text/Pandoc/Lua/Util.hs
@@ -1,6 +1,7 @@
 {-# LANGUAGE FlexibleInstances #-}
 {-# LANGUAGE LambdaCase #-}
 {-# LANGUAGE NoImplicitPrelude #-}
+{-# LANGUAGE OverloadedStrings #-}
 {- |
    Module      : Text.Pandoc.Lua.Util
    Copyright   : © 2012–2019 John MacFarlane,
@@ -31,9 +32,9 @@ import Control.Monad (unless, when)
 import Foreign.Lua ( Lua, NumArgs, NumResults, Peekable, Pushable, StackIndex
                    , Status, ToHaskellFunction )
 import Text.Pandoc.Class (readDataFile, runIOorExplode, setUserDataDir)
-
 import qualified Foreign.Lua as Lua
 import qualified Text.Pandoc.UTF8 as UTF8
+import Data.Text (Text)
 
 -- | Get value behind key from table at given index.
 rawField :: Peekable a => StackIndex -> String -> Lua a
@@ -104,7 +105,7 @@ getTag :: StackIndex -> Lua String
 getTag idx = do
   -- push metatable or just the table
   Lua.getmetatable idx >>= \hasMT -> unless hasMT (Lua.pushvalue idx)
-  Lua.push "tag"
+  Lua.push ("tag" :: Text)
   Lua.rawget (Lua.nthFromTop 2)
   Lua.tostring Lua.stackTop <* Lua.pop 2 >>= \case
     Nothing -> Lua.throwException "untagged value"