diff --git a/LICENSE b/LICENSE
--- a/LICENSE
+++ b/LICENSE
@@ -1,4 +1,4 @@
-Copyright (c) 2017 David Sorokin <david.sorokin@gmail.com>
+Copyright (c) 2018 David Sorokin <david.sorokin@gmail.com>
 
 All rights reserved.
 
diff --git a/Simulation/Aivika/GPSS/Block.hs b/Simulation/Aivika/GPSS/Block.hs
--- a/Simulation/Aivika/GPSS/Block.hs
+++ b/Simulation/Aivika/GPSS/Block.hs
@@ -23,7 +23,7 @@
 import Simulation.Aivika
 
 -- | Represents a GPSS block.
-data Block a b =
+newtype Block a b =
   Block { blockProcess :: a -> Process b
           -- ^ Process the item.
         }
diff --git a/Simulation/Aivika/Trans/GPSS/Block.hs b/Simulation/Aivika/Trans/GPSS/Block.hs
--- a/Simulation/Aivika/Trans/GPSS/Block.hs
+++ b/Simulation/Aivika/Trans/GPSS/Block.hs
@@ -23,7 +23,7 @@
 import Simulation.Aivika.Trans
 
 -- | Represents a GPSS block.
-data Block m a b =
+newtype Block m a b =
   Block { blockProcess :: a -> Process m b
           -- ^ Process the item.
         }
diff --git a/aivika-gpss.cabal b/aivika-gpss.cabal
--- a/aivika-gpss.cabal
+++ b/aivika-gpss.cabal
@@ -1,5 +1,5 @@
 name:            aivika-gpss
-version:         0.5
+version:         0.6
 synopsis:        GPSS-like DSL for Aivika
 description:
     This package allows defining simulation models in terms of a GPSS-like
@@ -40,7 +40,7 @@
 category:        Simulation
 license:         BSD3
 license-file:    LICENSE
-copyright:       (c) 2017. David Sorokin <david.sorokin@gmail.com>
+copyright:       (c) 2018. David Sorokin <david.sorokin@gmail.com>
 author:          David Sorokin
 maintainer:      David Sorokin <david.sorokin@gmail.com>
 homepage:        http://www.aivikasoft.com