diff --git a/README.md b/README.md
--- a/README.md
+++ b/README.md
@@ -1,4 +1,4 @@
-lucid
+lucid [![Hackage](https://img.shields.io/hackage/v/lucid.svg?style=flat)](https://hackage.haskell.org/package/lucid)
 =====
 
 Clear to write, read and edit DSL for writing HTML
diff --git a/lucid.cabal b/lucid.cabal
--- a/lucid.cabal
+++ b/lucid.cabal
@@ -1,5 +1,5 @@
 name:                lucid
-version:             2.4
+version:             2.5
 synopsis:            Clear to write, read and edit DSL for HTML
 description:         Clear to write, read and edit DSL for HTML. See the 'Lucid' module
                      for description and documentation.
diff --git a/src/Lucid/Base.hs b/src/Lucid/Base.hs
--- a/src/Lucid/Base.hs
+++ b/src/Lucid/Base.hs
@@ -78,7 +78,7 @@
          }
 
 -- | Monoid is right-associative, a la the 'Builder' in it.
-instance Monoid a => Monoid (Html a) where
+instance (Monoid a,Monad m) => Monoid (HtmlT m a) where
   mempty = HtmlT (return (\_ _ -> mempty,mempty))
   mappend (HtmlT get_f_a) (HtmlT get_g_b) =
     HtmlT (do ~(f,a) <- get_f_a