diff --git a/Text/Markdown.hs b/Text/Markdown.hs
--- a/Text/Markdown.hs
+++ b/Text/Markdown.hs
@@ -45,7 +45,7 @@
 
 -- | A newtype wrapper providing a @ToHtml@ instance.
 newtype Markdown = Markdown TL.Text
-  deriving(Eq, Monoid, IsString)
+  deriving(Eq, Ord, Monoid, IsString, Show)
 
 instance ToMarkup Markdown where
     toMarkup (Markdown t) = markdown def t
diff --git a/Text/Markdown/Block.hs b/Text/Markdown/Block.hs
--- a/Text/Markdown/Block.hs
+++ b/Text/Markdown/Block.hs
@@ -242,7 +242,7 @@
         Nothing -> False
         Just t' ->
             let (name, rest)
-                    | Just x <- T.stripPrefix "!--" t' = ("--", t')
+                    | Just _ <- T.stripPrefix "!--" t' = ("--", t')
                     | otherwise = T.break (\c -> c `elem` " >") t'
              in T.all isValidTagName name &&
                 not (T.null name) &&
diff --git a/markdown.cabal b/markdown.cabal
--- a/markdown.cabal
+++ b/markdown.cabal
@@ -1,5 +1,5 @@
 Name:                markdown
-Version:             0.1.9
+Version:             0.1.10
 Synopsis:            Convert Markdown to HTML, with XSS protection
 Description:         This library leverages existing high-performance libraries (attoparsec, blaze-html, text, and conduit), and should integrate well with existing codebases.
 Homepage:            https://github.com/snoyberg/markdown