diff --git a/semantic-diff.cabal b/semantic-diff.cabal
index 2c6918fac..46026583a 100644
--- a/semantic-diff.cabal
+++ b/semantic-diff.cabal
@@ -158,6 +158,7 @@ test-suite test
                      , array
                      , base
                      , bifunctors
+                     , bytestring
                      , deepseq
                      , filepath
                      , gitlib
diff --git a/test/DiffCommandSpec.hs b/test/DiffCommandSpec.hs
index 0b95b6db9..cdc47799d 100644
--- a/test/DiffCommandSpec.hs
+++ b/test/DiffCommandSpec.hs
@@ -9,8 +9,8 @@ import Prologue (($), fmap, (.), pure, for, panic)
 import Test.Hspec hiding (shouldBe, shouldNotBe, shouldThrow, errorCall)
 import Test.Hspec.Expectations.Pretty
 import Test.Hspec.LeanCheck
-import Data.Text.Lazy.Encoding as E
 import Data.Text.Lazy as T
+import qualified Data.ByteString.Lazy as BL
 import Data.Map
 import qualified Data.Vector as V
 import Arguments
@@ -58,7 +58,7 @@ spec = parallel $ do
 fetchDiffsOutput :: (Object -> Text) -> Arguments -> IO (Maybe (Map Text Value), Maybe (Map Text [Text]))
 fetchDiffsOutput f arguments = do
   diffs <- fetchDiffs arguments
-  let json = fromJust . decode . E.encodeUtf8 $ T.fromChunks [concatOutputs diffs]
+  let json = fromJust . decode . BL.fromStrict $ concatOutputs diffs
   pure (errors json, summaries f json)
 
 -- Diff Summaries payloads look like this:
diff --git a/test/IntegrationSpec.hs b/test/IntegrationSpec.hs
index c9fb427aa..a2c52b957 100644
--- a/test/IntegrationSpec.hs
+++ b/test/IntegrationSpec.hs
@@ -1,10 +1,12 @@
-{-# LANGUAGE DataKinds, GeneralizedNewtypeDeriving #-}
+{-# LANGUAGE DataKinds, GeneralizedNewtypeDeriving, OverloadedStrings #-}
 module IntegrationSpec where
 
 import Category as C
 import Data.Functor.Both
 import Data.Record
 import qualified Data.Text as T
+import qualified Data.ByteString as B
+import Data.Text.Encoding (decodeUtf8)
 import GHC.Show (Show(..))
 import Data.List (union, concat, transpose)
 import Info
@@ -109,7 +111,7 @@ testParse path expectedOutput = do
   let blob = sourceBlob source path
   term <- parserWithSource path blob
   let actual = (Verbatim . stripWhitespace) $ printTerm term 0 TreeOnly
-  expected <- (Verbatim . stripWhitespace) <$> readFile expectedOutput
+  expected <- (Verbatim . stripWhitespace) <$> B.readFile expectedOutput
   actual `shouldBe` expected
 
 testDiff :: Renderer (Record '[Range, Category, SourceSpan]) -> Both FilePath -> FilePath -> Expectation
@@ -117,7 +119,7 @@ testDiff renderer paths diff = do
   sources <- traverse readAndTranscodeFile' paths
   diff' <- diffFiles parser renderer (sourceBlobs sources)
   let actual = (Verbatim . stripWhitespace. concatOutputs . pure) diff'
-  expected <- (Verbatim . stripWhitespace) <$> readFile diff
+  expected <- (Verbatim . stripWhitespace) <$> B.readFile diff
   actual `shouldBe` expected
   where
     parser = parserForFilepath filePath
@@ -126,14 +128,14 @@ testDiff renderer paths diff = do
                                | otherwise = readAndTranscodeFile path
     filePath = if fst paths /= "" then fst paths else snd paths
 
-stripWhitespace :: Text -> Text
-stripWhitespace = T.foldl' go T.empty
-  where go acc x | x `elem` [' ', '\t', '\n'] = acc
-                 | otherwise = T.snoc acc x
+stripWhitespace :: ByteString -> ByteString
+stripWhitespace = B.foldl' go B.empty
+  where go acc x | x `B.elem` " \t\n" = acc
+                 | otherwise = B.snoc acc x
 
--- | A wrapper around `Text` with a more readable `Show` instance.
-newtype Verbatim = Verbatim Text
+-- | A wrapper around `ByteString` with a more readable `Show` instance.
+newtype Verbatim = Verbatim ByteString
   deriving (Eq, NFData)
 
 instance Show Verbatim where
-  showsPrec _ (Verbatim text) = ('\n':) . (T.unpack text ++)
+  showsPrec _ (Verbatim byteString) = ('\n':) . (T.unpack (decodeUtf8 byteString) ++)
diff --git a/test/TOCSpec.hs b/test/TOCSpec.hs
index 5db9365de..9a298e77c 100644
--- a/test/TOCSpec.hs
+++ b/test/TOCSpec.hs
@@ -112,13 +112,13 @@ spec = parallel $ do
       sourceBlobs <- blobsForPaths (both "ruby/methods.A.rb" "ruby/methods.B.rb")
       let parser = parserForFilepath (path (fst sourceBlobs))
       output <- diffFiles parser toc sourceBlobs
-      concatOutputs (pure output) `shouldBe` ("{\"changes\":{\"ruby/methods.A.rb -> ruby/methods.B.rb\":[{\"span\":{\"start\":[1,1],\"end\":[2,4]},\"category\":\"Method\",\"term\":\"self.foo\",\"changeType\":\"added\"},{\"span\":{\"start\":[4,1],\"end\":[6,4]},\"category\":\"Method\",\"term\":\"bar\",\"changeType\":\"modified\"},{\"span\":{\"start\":[4,1],\"end\":[5,4]},\"category\":\"Method\",\"term\":\"baz\",\"changeType\":\"removed\"}]},\"errors\":{}}" :: Text)
+      concatOutputs (pure output) `shouldBe` ("{\"changes\":{\"ruby/methods.A.rb -> ruby/methods.B.rb\":[{\"span\":{\"start\":[1,1],\"end\":[2,4]},\"category\":\"Method\",\"term\":\"self.foo\",\"changeType\":\"added\"},{\"span\":{\"start\":[4,1],\"end\":[6,4]},\"category\":\"Method\",\"term\":\"bar\",\"changeType\":\"modified\"},{\"span\":{\"start\":[4,1],\"end\":[5,4]},\"category\":\"Method\",\"term\":\"baz\",\"changeType\":\"removed\"}]},\"errors\":{}}" )
 
     it "encodes to final JSON if there are parse errors" $ do
       sourceBlobs <- blobsForPaths (both "ruby/methods.A.rb" "ruby/methods.X.rb")
       let parser = parserForFilepath (path (fst sourceBlobs))
       output <- diffFiles parser toc sourceBlobs
-      concatOutputs (pure output) `shouldBe` ("{\"changes\":{},\"errors\":{\"ruby/methods.A.rb -> ruby/methods.X.rb\":[{\"span\":{\"start\":[1,1],\"end\":[3,1]},\"error\":\"def bar\\nen\\n\"}]}}" :: Text)
+      concatOutputs (pure output) `shouldBe` ("{\"changes\":{},\"errors\":{\"ruby/methods.A.rb -> ruby/methods.X.rb\":[{\"span\":{\"start\":[1,1],\"end\":[3,1]},\"error\":\"def bar\\nen\\n\"}]}}" )
 
 type Diff' = SyntaxDiff String '[Range, Category, SourceSpan]
 type Term' = SyntaxTerm String '[Range, Category, SourceSpan]