diff --git a/glpk-headers.cabal b/glpk-headers.cabal
--- a/glpk-headers.cabal
+++ b/glpk-headers.cabal
@@ -4,15 +4,15 @@
 --
 -- see: https://github.com/sol/hpack
 --
--- hash: b341ce52a0373ed5e6ed9fe67ce9b26b00173d6049138e819b55fc4cc941399a
+-- hash: 201535c79f43ed6acaf4fa8a43ee68a5958c4c3bbc5118381c9c3cbfdfa226df
 
 name:           glpk-headers
-version:        0.3.0
+version:        0.4.0
 synopsis:       Low-level Haskell bindings to GLPK.
-description:    Please see the README on GitHub at <https://github.com/prsteele/GlpkHs#readme>
+description:    Please see the README on GitHub at <https://github.com/prsteele/glpk-headers-haskell#readme>
 category:       Math
-homepage:       https://github.com/prsteele/GlpkHs#readme
-bug-reports:    https://github.com/prsteele/GlpkHs/issues
+homepage:       https://github.com/prsteele/glpk-headers-haskell#readme
+bug-reports:    https://github.com/prsteele/glpk-headers-haskell/issues
 author:         Patrick Steele
 maintainer:     steele.pat@gmail.com
 copyright:      2018 Patrick Steele
@@ -25,7 +25,7 @@
 
 source-repository head
   type: git
-  location: https://github.com/prsteele/GlpkHs
+  location: https://github.com/prsteele/glpk-headers-haskell
 
 library
   exposed-modules:
diff --git a/src/Math/Programming/Glpk/Header.hsc b/src/Math/Programming/Glpk/Header.hsc
--- a/src/Math/Programming/Glpk/Header.hsc
+++ b/src/Math/Programming/Glpk/Header.hsc
@@ -33,7 +33,7 @@
   , FixedLengthArray (..)
 
     -- ** Low-level and phantom types
-  , GlpkInt
+  , GlpkInt (..)
   , Problem
   , GlpkColumn
   , GlpkRow
@@ -64,7 +64,7 @@
   , GlpkDirection
   , glpkMin
   , glpkMax
-  , GlpkVariableType
+  , GlpkVariableType (..)
   , glpkContinuous
   , glpkInteger
   , glpkBinary