diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,17 @@
+HEAD
+---
+* ...
+
+0.7.1.0
+---
+* Support for ()
+* Remove redundant `Lookup a` constraint on `Lookup (V0 a)`
+* Switch Bool from basic type to sum type.
+
+0.7.0.0
+---
+* Break Int into several integer types.
+
 0.6.2.0
 ---
 * bugfix diffDTree
diff --git a/generic-accessors.cabal b/generic-accessors.cabal
--- a/generic-accessors.cabal
+++ b/generic-accessors.cabal
@@ -1,5 +1,5 @@
 name:                generic-accessors
-version:             0.7.0.0
+version:             0.7.1.0
 synopsis:            stringly-named getters for generic data
 license:             BSD3
 license-file:        LICENSE
diff --git a/src/Accessors/Accessors.hs b/src/Accessors/Accessors.hs
--- a/src/Accessors/Accessors.hs
+++ b/src/Accessors/Accessors.hs
@@ -62,6 +62,7 @@
   | FieldWord32 (Lens' a Word32)
   | FieldWord64 (Lens' a Word64)
   | FieldString (Lens' a String)
+  | FieldUnit
   | FieldSorry -- ^ a field which is not yet supported
 
 data GATip a =
@@ -104,6 +105,7 @@
 describeGAField (FieldWord32 _) = "Word32"
 describeGAField (FieldWord64 _) = "Word64"
 describeGAField (FieldString _) = "String"
+describeGAField FieldUnit = "()"
 describeGAField FieldSorry      = "Sorry"
 
 -- | Returns True if the __type__ of fields is the same.
@@ -119,6 +121,7 @@
 sameFieldType (FieldWord32 _) (FieldWord32 _) = True
 sameFieldType (FieldWord64 _) (FieldWord64 _) = True
 sameFieldType (FieldString _) (FieldString _) = True
+sameFieldType FieldUnit FieldUnit              = True
 sameFieldType FieldSorry FieldSorry           = True
 sameFieldType (FieldDouble _)  _              = False
 sameFieldType (FieldFloat _)   _              = False
@@ -131,6 +134,7 @@
 sameFieldType (FieldWord32 _)  _              = False
 sameFieldType (FieldWord64 _)  _              = False
 sameFieldType (FieldString _)  _              = False
+sameFieldType FieldUnit        _              = False
 sameFieldType FieldSorry       _              = False
 
 accessors :: Lookup a => AccessorTree a
@@ -376,6 +380,7 @@
 showFieldVal (FieldDouble lens) show' x = show' (x ^. lens)
 showFieldVal (FieldFloat lens) show' x = show' (realToFrac (x ^. lens))
 showFieldVal (FieldString lens) _ x = x ^. lens
+showFieldVal FieldUnit _ _ = "()"
 showFieldVal FieldSorry _ _ = ""
 
 showTipVal :: GATip a -> (Double -> String) -> a -> String
diff --git a/src/Accessors/Dynamic.hs b/src/Accessors/Dynamic.hs
--- a/src/Accessors/Dynamic.hs
+++ b/src/Accessors/Dynamic.hs
@@ -58,6 +58,7 @@
   | DWord32 Word32
   | DWord64 Word64
   | DString String
+  | DUnit
   | DSorry
   deriving (Generic, Show, Eq, Ord, Data, Typeable)
 instance Serialize DField
@@ -112,6 +113,7 @@
 sameDFieldType (DWord32 _) (DWord32 _) = True
 sameDFieldType (DWord64 _) (DWord64 _) = True
 sameDFieldType (DString _) (DString _) = True
+sameDFieldType DUnit DUnit             = True
 sameDFieldType DSorry DSorry           = True
 sameDFieldType (DDouble _) _           = False
 sameDFieldType (DFloat _)  _           = False
@@ -124,6 +126,7 @@
 sameDFieldType (DWord32 _) _           = False
 sameDFieldType (DWord64 _) _           = False
 sameDFieldType (DString _) _           = False
+sameDFieldType DUnit       _           = False
 sameDFieldType DSorry      _           = False
 
 describeDField :: DField -> String
@@ -138,6 +141,7 @@
 describeDField (DDouble _) = "Double"
 describeDField (DFloat _)  = "Float"
 describeDField (DString _) = "String"
+describeDField DUnit       = "()"
 describeDField DSorry      = "Sorry"
 
 -- | convert to a dynamic value
@@ -168,6 +172,7 @@
     toDField (FieldWord32 f) = DWord32 (x ^. f)
     toDField (FieldWord64 f) = DWord64 (x ^. f)
     toDField (FieldString f) = DString (x ^. f)
+    toDField FieldUnit       = DUnit
     toDField FieldSorry      = DSorry
 
 
@@ -255,6 +260,7 @@
 updateField x0 (FieldWord32 f) (DWord32 x) = Right $ (f .~ x) x0
 updateField x0 (FieldWord64 f) (DWord64 x) = Right $ (f .~ x) x0
 updateField x0 (FieldString f) (DString x) = Right $ (f .~ x) x0
+updateField x0 FieldUnit _                 = Right x0
 updateField x0 FieldSorry _                = Right x0
 updateField _ f@(FieldDouble _) d          = Left (fieldMismatch f d)
 updateField _ f@(FieldFloat _)  d          = Left (fieldMismatch f d)
diff --git a/src/Accessors/Instances.hs b/src/Accessors/Instances.hs
--- a/src/Accessors/Instances.hs
+++ b/src/Accessors/Instances.hs
@@ -72,7 +72,7 @@
 -- TODO(MP): Product?  Const?  Identity?
 
 -- some instance from linear
-instance Lookup a => Lookup (Linear.V0 a) where
+instance Lookup (Linear.V0 a) where
   toAccessorTree _ =
     Right $ GAData "V0" $ GAConstructor "V0" []
 instance Lookup a => Lookup (Linear.V1 a) where
@@ -112,8 +112,8 @@
     ]
 
 -- basic types
-instance Lookup () where -- hack to get dummy tree
-  toAccessorTree _ = Left FieldSorry
+instance Lookup () where
+  toAccessorTree _ = Left FieldUnit
 instance Lookup Int8 where
   toAccessorTree lens = Left (FieldInt8 lens)
 instance Lookup Int16 where