diff --git a/protocol.cabal b/protocol.cabal
--- a/protocol.cabal
+++ b/protocol.cabal
@@ -4,10 +4,10 @@
 --
 -- see: https://github.com/sol/hpack
 --
--- hash: 891acf4772c5e0911b5e56fb7dd8b4a457d91866ed95b4a3142d852a9c0b9b2a
+-- hash: 4d3ce4b652d9148b159ca371ae80cb101f7189dbef8e358d0d33e8a336babefd
 
 name:           protocol
-version:        0.1.0.0
+version:        0.1.0.1
 synopsis:       Model distributed system as type-level multi-party protocol
 description:    This package provides type to model distributed multi-party protocols,
                 ensuring the continuity of the associated resource state transitions on the type level
@@ -42,5 +42,5 @@
   build-depends:
       base >=4.7 && <5
     , freer-indexed ==0.1.*
-    , singletons ==2.6.*
+    , singletons >=2.5 && <2.8
   default-language: Haskell2010
diff --git a/src/Control/Protocol/Example.hs b/src/Control/Protocol/Example.hs
--- a/src/Control/Protocol/Example.hs
+++ b/src/Control/Protocol/Example.hs
@@ -6,6 +6,7 @@
 {-# LANGUAGE RankNTypes #-}
 {-# LANGUAGE RebindableSyntax #-}
 {-# LANGUAGE ScopedTypeVariables #-}
+{-# LANGUAGE StandaloneDeriving #-}
 {-# LANGUAGE TemplateHaskell #-}
 {-# LANGUAGE TypeApplications #-}
 {-# LANGUAGE TypeFamilies #-}