diff --git a/CHANGELOG b/CHANGELOG
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -1,5 +1,9 @@
 # CHANGELOG
 
+- 0.6.4.0
+    * Remove `XmlSyntax` from whitelisted language extensions, since it was
+      causing parsing errors
+
 - 0.6.3.0
     * Bump `optparse-applicative` to 0.13.0.0
     * Export Import options & add a default
diff --git a/lib/Language/Haskell/Stylish/Parse.hs b/lib/Language/Haskell/Stylish/Parse.hs
--- a/lib/Language/Haskell/Stylish/Parse.hs
+++ b/lib/Language/Haskell/Stylish/Parse.hs
@@ -29,7 +29,6 @@
   , H.PatternGuards
   , H.StandaloneDeriving
   , H.UnicodeSyntax
-  , H.XmlSyntax
   ]
 
 
diff --git a/stylish-haskell.cabal b/stylish-haskell.cabal
--- a/stylish-haskell.cabal
+++ b/stylish-haskell.cabal
@@ -1,5 +1,5 @@
 Name:          stylish-haskell
-Version:       0.6.3.0
+Version:       0.6.4.0
 Synopsis:      Haskell code prettifier
 Homepage:      https://github.com/jaspervdj/stylish-haskell
 License:       BSD3
diff --git a/tests/Language/Haskell/Stylish/Parse/Tests.hs b/tests/Language/Haskell/Stylish/Parse/Tests.hs
--- a/tests/Language/Haskell/Stylish/Parse/Tests.hs
+++ b/tests/Language/Haskell/Stylish/Parse/Tests.hs
@@ -26,6 +26,7 @@
     , testCase "KindSignatures extension"    testKindSignatures
     , testCase "StandalonDeriving extension" testStandaloneDeriving
     , testCase "UnicodeSyntax extension"     testUnicodeSyntax
+    , testCase "XmlSyntax regression"        testXmlSyntaxRegression
     ]
 
 --------------------------------------------------------------------------------
@@ -112,6 +113,11 @@
   [ "module Main where"
   , "monadic ∷ (Monad m) ⇒ m a → m a"
   , "monadic = id"
+  ]
+
+testXmlSyntaxRegression :: Assertion
+testXmlSyntaxRegression = assert $ isRight $ parseModule [] Nothing $ unlines
+  [ "smaller a b = a <b"
   ]
 
 --------------------------------------------------------------------------------