diff --git a/LICENSE b/LICENSE
deleted file mode 100644
--- a/LICENSE
+++ /dev/null
@@ -1,30 +0,0 @@
-Copyright (c) 2015, Tweag I/O Limited
-
-All rights reserved.
-
-Redistribution and use in source and binary forms, with or without
-modification, are permitted provided that the following conditions are met:
-
-    * Redistributions of source code must retain the above copyright
-      notice, this list of conditions and the following disclaimer.
-
-    * Redistributions in binary form must reproduce the above
-      copyright notice, this list of conditions and the following
-      disclaimer in the documentation and/or other materials provided
-      with the distribution.
-
-    * Neither the name of Mathieu Boespflug nor the names of other
-      contributors may be used to endorse or promote products derived
-      from this software without specific prior written permission.
-
-THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
-"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
-LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
-A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
-OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
-SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
-LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
-DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
-THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
-(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
-OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
diff --git a/LICENSE.md b/LICENSE.md
new file mode 100644
--- /dev/null
+++ b/LICENSE.md
@@ -0,0 +1,30 @@
+Copyright (c) 2015, Tweag I/O Limited
+
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+    * Redistributions of source code must retain the above copyright
+      notice, this list of conditions and the following disclaimer.
+
+    * Redistributions in binary form must reproduce the above
+      copyright notice, this list of conditions and the following
+      disclaimer in the documentation and/or other materials provided
+      with the distribution.
+
+    * Neither the name of Mathieu Boespflug nor the names of other
+      contributors may be used to endorse or promote products derived
+      from this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
diff --git a/distributed-closure.cabal b/distributed-closure.cabal
--- a/distributed-closure.cabal
+++ b/distributed-closure.cabal
@@ -1,62 +1,89 @@
-name:                distributed-closure
-version:             0.4.2.0
-synopsis:            Serializable closures for distributed programming.
-description:         See README.
-homepage:            https://github.com/tweag/distributed-closure
-license:             BSD3
-license-file:        LICENSE
-author:              Mathieu Boespflug
-maintainer:          m@tweag.io
-copyright:           © Tweag I/O Limited
-category:            Control
-build-type:          Simple
-extra-source-files:  README.md
-cabal-version:       >=1.10
+name: distributed-closure
+version: 0.5.0.0
+synopsis: Serializable closures for distributed programming.
+description: See README.
+homepage: https://github.com/tweag/distributed-closure
+license: BSD3
+license-file: LICENSE.md
+author: Mathieu Boespflug
+maintainer: m@tweag.io
+copyright: © Tweag I/O Limited
+category: Control
+build-type: Simple
+extra-source-files: README.md
+cabal-version: >=1.10
 
 source-repository head
-  type:     git
+  type: git
   location: https://github.com/tweag/distributed-closure
 
+flag dev
+  description: Turn on development settings.
+  manual: True
+  default: False
+
 library
-  exposed-modules:     Control.Applicative.Static
-                       Control.Comonad.Static
-                       Control.Distributed.Closure
-                       Control.Distributed.Closure.Internal
-                       Control.Distributed.Closure.TH
-                       Control.Monad.Static
-                       Data.Profunctor.Static
-                       Data.Profunctor.Choice.Static
-                       Data.Profunctor.Strong.Static
-                       Data.Functor.Static
-  build-depends:       base >=4.11 && <5
-                     , binary >= 0.7.5
-                     , bytestring >= 0.10
-                     , constraints >= 0.4
-                     , syb >= 0.5
-                     , template-haskell >= 2.10
-  hs-source-dirs:      src
-  default-language:    Haskell2010
-  ghc-options:         -Wall
+  exposed-modules:
+    Control.Applicative.Static
+    Control.Comonad.Static
+    Control.Distributed.Closure
+    Control.Distributed.Closure.Internal
+    Control.Distributed.Closure.TH
+    Control.Monad.Static
+    Data.Profunctor.Static
+    Data.Profunctor.Choice.Static
+    Data.Profunctor.Strong.Static
+    Data.Functor.Static
+  build-depends:
+    base >=4.11 && <5,
+    binary >= 0.7.5,
+    bytestring >= 0.10,
+    constraints >= 0.4,
+    syb >= 0.5,
+    template-haskell >= 2.10
+  hs-source-dirs: src
+  default-language: Haskell2010
+  if flag(dev)
+    ghc-options: -Wall -Werror -Wcompat
+                 -Wincomplete-record-updates
+                 -Wincomplete-uni-patterns
+                 -Wnoncanonical-monad-instances
+  else
+    ghc-options: -Wall
 
 test-suite tests
-  type:             exitcode-stdio-1.0
+  type: exitcode-stdio-1.0
   default-language: Haskell2010
-  hs-source-dirs:   tests
-  main-is:          test.hs
-  ghc-options:      -Wall
-  Build-Depends:    base >= 4.8,
-                    binary >= 0.7,
-                    distributed-closure,
-                    hspec >= 2.1,
-                    QuickCheck >= 2.8
+  hs-source-dirs: tests
+  main-is: test.hs
+  build-depends:
+    base >= 4.8,
+    binary >= 0.7,
+    distributed-closure,
+    hspec >= 2.1,
+    QuickCheck >= 2.8
+  if flag(dev)
+    ghc-options: -Wall -Werror -Wcompat
+                 -Wincomplete-record-updates
+                 -Wincomplete-uni-patterns
+                 -Wnoncanonical-monad-instances
+  else
+    ghc-options: -Wall
 
 executable example-client-server
-  main-is:          ClientServer.hs
-  hs-source-dirs:   examples
+  main-is: ClientServer.hs
+  hs-source-dirs: examples
   default-language: Haskell2010
-  ghc-options:      -Wall
-  build-depends:    base >= 4.8
-                  , async >= 2.1
-                  , binary >= 0.7
-                  , bytestring >= 0.10
-                  , distributed-closure
+  build-depends:
+    base >= 4.8,
+    async >= 2.1,
+    binary >= 0.7,
+    bytestring >= 0.10,
+    distributed-closure
+  if flag(dev)
+    ghc-options: -Wall -Werror -Wcompat
+                 -Wincomplete-record-updates
+                 -Wincomplete-uni-patterns
+                 -Wnoncanonical-monad-instances
+  else
+    ghc-options: -Wall
diff --git a/src/Control/Applicative/Static.hs b/src/Control/Applicative/Static.hs
--- a/src/Control/Applicative/Static.hs
+++ b/src/Control/Applicative/Static.hs
@@ -20,7 +20,10 @@
     -> f b
 
 class StaticApply f => StaticApplicative f where
-  staticPure :: Typeable a => a -> f a
+  staticPure :: Typeable a => Closure a -> f a
 
 instance StaticApply Closure where
   staticApply = cap
+
+instance StaticApplicative Closure where
+  staticPure = id
diff --git a/src/Control/Distributed/Closure/TH.hs b/src/Control/Distributed/Closure/TH.hs
--- a/src/Control/Distributed/Closure/TH.hs
+++ b/src/Control/Distributed/Closure/TH.hs
@@ -117,7 +117,14 @@
         f <- mangleName <$> TH.newName "static_helper"
         fbody <- foldr (\_ body -> [| \Dict -> $body |]) [| Dict |] cxt
         let tyf = foldr (\a b -> TH.ArrowT `TH.AppT` a `TH.AppT` b) retsig dictsigs
-            sigf = TH.SigD f (TH.ForallT (map TH.PlainTV (fvT tyf)) [] tyf)
+#if MIN_VERSION_template_haskell(2,16,0)
+            specifiedPlainTV :: TH.Name -> TH.TyVarBndr TH.Specificity
+            specifiedPlainTV n = TH.PlainTV n TH.SpecifiedSpec
+#else
+            specifiedPlainTV :: TH.Name -> TH.TyVarBndr
+            specifiedPlainTV = TH.PlainTV
+#endif
+            sigf = TH.SigD f (TH.ForallT (map specifiedPlainTV (fvT tyf)) [] tyf)
             declf = TH.ValD (TH.VarP f) (TH.NormalB fbody) []
         methods <- (:[]) <$>
           TH.valD
diff --git a/src/Control/Monad/Static.hs b/src/Control/Monad/Static.hs
--- a/src/Control/Monad/Static.hs
+++ b/src/Control/Monad/Static.hs
@@ -36,7 +36,7 @@
 class (StaticApplicative m, StaticBind m) => StaticMonad m
 instance (StaticApplicative m, StaticBind m) => StaticMonad m
 
-staticReturn :: (StaticApplicative m, Typeable a) => a -> m a
+staticReturn :: (StaticApplicative m, Typeable a) => Closure a -> m a
 staticReturn = staticPure
 
 instance StaticBind Closure where