diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,15 @@
 # Revision history for red-black-record
 
+## 2.0.4.0
+
+- Compatibility with sop-core 0.5.0.0.
+- Contravariant intance for Case newtype.
+
+## 2.0.3.0
+
+- Issue #7: FromVariant & ToVariant instances for sum types with branches with
+  no arguments.
+
 ## 2.0.2.2
 
 - Improved compilation times for type-level deletion.
diff --git a/lib/Data/RBR/Internal.hs b/lib/Data/RBR/Internal.hs
--- a/lib/Data/RBR/Internal.hs
+++ b/lib/Data/RBR/Internal.hs
@@ -32,6 +32,7 @@
 import           Data.Kind
 import           Data.Typeable
 import           Data.Coerce
+import           Data.Functor.Contravariant (Contravariant(contramap))
 import           Data.Bifunctor (first)
 import           Data.Monoid (Endo(..))
 import           Data.List (intersperse)
@@ -702,6 +703,9 @@
 {- | Represents a handler for a branch of a 'Variant'.  
 -}
 newtype Case f a b = Case (f b -> a)
+
+instance Functor f => Contravariant (Case f a) where
+    contramap g (Case c) = Case (c . fmap g)
 
 {- | A form of 'addField' for creating eliminators for 'Variant's.
 -}
diff --git a/red-black-record.cabal b/red-black-record.cabal
--- a/red-black-record.cabal
+++ b/red-black-record.cabal
@@ -1,6 +1,6 @@
 cabal-version:       2.0
 name:                red-black-record
-version:             2.0.3.0
+version:             2.0.4.0
 synopsis:            Extensible records and variants indexed by a type-level Red-Black tree.
 
 description:         A library that provides extensible records and variants,
@@ -35,14 +35,14 @@
                        Data.RBR.Internal
                        Data.RBR.Examples
   build-depends:       base                 >= 4.10.0.0 && < 5,
-                       sop-core             >= 0.4.0.0 && < 0.5
+                       sop-core             >= 0.4.0.0 && < 0.6
   hs-source-dirs:      lib
   default-language:    Haskell2010
 
 library demoted
   exposed-modules:     Data.RBR.Demoted
   build-depends:       base                 >= 4.10.0.0 && < 5,
-                       sop-core             >= 0.4.0.0 && < 0.5,
+                       sop-core             >= 0.4.0.0 && < 0.6,
                        red-black-record
   hs-source-dirs:      lib-demoted
   default-language:    Haskell2010
@@ -53,7 +53,7 @@
   ghc-options:         -threaded
   main-is:             doctests.hs
   build-depends:       base                 >= 4.10.0.0 && < 5,
-                       sop-core             >= 0.4.0.0 && < 0.5,
+                       sop-core             >= 0.4.0.0 && < 0.6,
                        red-black-record,
                        aeson                >= 1.4.0.0 && < 1.5,
                        bytestring           >= 0.10,
@@ -68,7 +68,7 @@
   main-is:             tests.hs
   build-depends:
                        base                 >= 4.10.0.0 && < 5,
-                       sop-core             >= 0.4.0.0 && < 0.5,
+                       sop-core             >= 0.4.0.0 && < 0.6,
                        tasty                >= 0.10.1.1,
                        tasty-hunit          >= 0.9.2,
                        red-black-record,