diff --git a/hakyll.cabal b/hakyll.cabal
--- a/hakyll.cabal
+++ b/hakyll.cabal
@@ -1,5 +1,5 @@
 Name:               hakyll
-Version:            3.1.1.1
+Version:            3.1.1.2
 
 Synopsis:           A simple static site generator library.
 Description:        A simple static site generator library, mainly aimed at
diff --git a/src/Hakyll/Core/Writable.hs b/src/Hakyll/Core/Writable.hs
--- a/src/Hakyll/Core/Writable.hs
+++ b/src/Hakyll/Core/Writable.hs
@@ -11,6 +11,8 @@
 import Text.Blaze (Html)
 import Text.Blaze.Renderer.String (renderHtml)
 
+import Hakyll.Core.Identifier
+
 -- | Describes an item that can be saved to the disk
 --
 class Writable a where
@@ -28,3 +30,6 @@
 
 instance Writable Html where
     write p html = write p $ renderHtml html
+
+instance Writable Identifier where
+    write p i = write p $ show i