diff --git a/Data/Bson.hs b/Data/Bson.hs
--- a/Data/Bson.hs
+++ b/Data/Bson.hs
@@ -148,7 +148,7 @@
 	ObjId x -> f x
 	Bool x -> f x
 	UTC x -> f x
-	Null -> f ()
+	Null -> f (Nothing :: Maybe Value)
 	RegEx x -> f x
 	JavaScr x -> f x
 	Sym x -> f x
@@ -265,10 +265,17 @@
 	cast' (UTC x) = Just (utcTimeToPOSIXSeconds x)
 	cast' _ = Nothing
 
-instance Val () where
-	val () = Null
-	cast' Null = Just ()
-	cast' _ = Nothing
+instance Val (Maybe Value) where
+	val Nothing = Null
+	val (Just v) = v
+	cast' Null = Just Nothing
+	cast' v = Just (Just v)
+
+instance (Val a) => Val (Maybe a) where
+	val Nothing = Null
+	val (Just a) = val a
+	cast' Null = Just Nothing
+	cast' v = fmap Just (cast' v)
 
 instance Val Regex where
 	val = RegEx
diff --git a/bson.cabal b/bson.cabal
--- a/bson.cabal
+++ b/bson.cabal
@@ -1,5 +1,5 @@
 Name: bson
-Version: 0.0.4
+Version: 0.1
 Synopsis: BSON documents are JSON-like objects with a standard binary encoding
 Description: A BSON Document is an untyped (dynamically type-checked) record. I.e. it is a list of name-value pairs, where a Value is a single sum type with constructors for basic types (Bool, Int, Float, String, and Time), compound types (List, and (embedded) Document), and special types (Binary, Javascript, ObjectId, RegEx, and a few others).
 	.