diff --git a/ChangeLog.md b/ChangeLog.md
new file mode 100644
--- /dev/null
+++ b/ChangeLog.md
@@ -0,0 +1,5 @@
+# Revision history for data-inttrie
+
+## 0.1.2  -- YYYY-mm-dd
+
+* First version. Released on an unsuspecting world.
diff --git a/Data/IntTrie.hs b/Data/IntTrie.hs
--- a/Data/IntTrie.hs
+++ b/Data/IntTrie.hs
@@ -26,6 +26,7 @@
 import Data.Bits
 import Data.Function (fix)
 import Data.Monoid (Monoid(..))
+import Data.Semigroup (Semigroup(..))
 
 -- | A trie from integers to values of type a. 
 -- 
@@ -41,6 +42,9 @@
     pure x = fix (\g -> BitTrie x g g)
     ~(BitTrie f fl fr) <*> ~(BitTrie x xl xr) = BitTrie (f x) (fl <*> xl) (fr <*> xr)
 
+instance Semigroup a => Semigroup (BitTrie a) where
+    (<>) = liftA2 (<>)
+
 instance Monoid a => Monoid (BitTrie a) where
     mempty = pure mempty
     mappend = liftA2 mappend
@@ -52,6 +56,9 @@
     pure x = IntTrie (pure x) x (pure x)
     IntTrie fneg fz fpos <*> IntTrie xneg xz xpos = 
         IntTrie (fneg <*> xneg) (fz xz) (fpos <*> xpos)
+
+instance Semigroup a => Semigroup (IntTrie a) where
+    (<>) = liftA2 (<>)
 
 instance Monoid a => Monoid (IntTrie a) where
     mempty = pure mempty
diff --git a/LICENSE b/LICENSE
new file mode 100644
--- /dev/null
+++ b/LICENSE
@@ -0,0 +1,30 @@
+Copyright (c) 2018, Luke Palmer
+
+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 Luke Palmer 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/Setup.hs b/Setup.hs
--- a/Setup.hs
+++ b/Setup.hs
@@ -1,3 +1,2 @@
 import Distribution.Simple
-main :: IO ()
 main = defaultMain
diff --git a/data-inttrie.cabal b/data-inttrie.cabal
--- a/data-inttrie.cabal
+++ b/data-inttrie.cabal
@@ -1,14 +1,25 @@
-Name: data-inttrie
-Description:
-    A simple lazy, infinite trie from integers.
-Version: 0.1.2
-Stability: experimental
-Synopsis: A lazy, infinite trie of integers.
-License: BSD3
-Category: Data
-Author: Luke Palmer <lrpalmer@gmail.com>
-Homepage: http://github.com/luqui/data-inttrie
-Maintainer: Luke Palmer <lrpalmer@gmail.com>
-Build-Type: Simple
-Build-Depends: base >= 3 && < 5
-Exposed-Modules: Data.IntTrie
+-- Initial data-inttrie.cabal generated by cabal init.  For further 
+-- documentation, see http://haskell.org/cabal/users-guide/
+
+name:                data-inttrie
+version:             0.1.3
+synopsis:            A simple lazy, infinite trie from integers
+-- description:         
+homepage:            https://github.com/luqui/data-inttrie
+license:             BSD3
+license-file:        LICENSE
+author:              Luke Palmer
+maintainer:          lrpalmer@gmail.com
+-- copyright:           
+category:            Data
+build-type:          Simple
+extra-source-files:  ChangeLog.md
+cabal-version:       >=1.10
+
+library
+  exposed-modules:     Data.IntTrie
+  -- other-modules:       
+  -- other-extensions:    
+  build-depends:       base >=4.10 && <4.11
+  -- hs-source-dirs:      
+  default-language:    Haskell2010