diff --git a/.travis.yml b/.travis.yml
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,49 +1,55 @@
-language: haskell
+# NB: don't set `language: haskell` here
 
+# See also https://github.com/hvr/multi-ghc-travis for more information
 env:
-  - GHCVER=7.8.3
-  - GHCVER=head
+ # we have to use CABALVER=1.16 for GHC<7.6 as well, as there's
+ # no package for earlier cabal versions in the PPA
+ - GHCVER=7.4.2 CABALVER=1.16
+ - GHCVER=7.6.3 CABALVER=1.16
+ - GHCVER=7.8.4 CABALVER=1.18
+ - GHCVER=7.10.1 CABALVER=1.22
+ - GHCVER=head CABALVER=1.22
 
 matrix:
   allow_failures:
-    - env: GHCVER=head
+   - env: GHCVER=head CABALVER=1.22
 
+# Note: the distinction between `before_install` and `install` is not
+#       important.
 before_install:
-  # If $GHCVER is the one travis has, don't bother reinstalling it.
-  # We can also have faster builds by installing some libraries with
-  # `apt`. If it isn't, install the GHC we want from hvr's PPA along
-  # with cabal-1.18.
-  - |
-    if [ $GHCVER = `ghc --numeric-version` ]; then
-      # Try installing some of the build-deps with apt-get for speed.
-      travis/cabal-apt-install --enable-tests $MODE
-      export CABAL=cabal
-    else
-      # Install the GHC we want from hvr's PPA
-      travis_retry sudo add-apt-repository -y ppa:hvr/ghc
-      travis_retry sudo apt-get update
-      travis_retry sudo apt-get install cabal-install-1.18 ghc-$GHCVER happy
-      export CABAL=cabal-1.18
-      export PATH=/opt/ghc/$GHCVER/bin:$PATH
-    fi
-  # Uncomment whenever hackage is down.
-  # - mkdir -p ~/.cabal && cp travis/config ~/.cabal/config && $CABAL update
-  - $CABAL update
-
-  # Update happy when building with GHC head
-  - |
-    if [ $GHCVER = "head" ] || [ $GHCVER = "7.8.3" ]; then
-      $CABAL install happy alex
-      export PATH=$HOME/.cabal/bin:$PATH
-    fi
+ - travis_retry sudo add-apt-repository -y ppa:hvr/ghc
+ - travis_retry sudo apt-get update
+ - travis_retry sudo apt-get install cabal-install-$CABALVER ghc-$GHCVER
+ - export PATH=/opt/ghc/$GHCVER/bin:/opt/cabal/$CABALVER/bin:$PATH
+ - cabal --version
 
 install:
-  - $CABAL install --dependencies-only --enable-tests
-  - $CABAL configure --enable-tests $MODE
+ - travis_retry cabal update
+ - cabal install --only-dependencies
 
+# Here starts the actual work to be performed for the package under
+# test; any command which exits with a non-zero exit code causes the
+# build to fail.
 script:
-  - $CABAL build
-  - $CABAL test --show-details=always
+ # -v2 provides useful information for debugging
+ - cabal configure -v2
+
+ # this builds all libraries and executables
+ # (including tests/benchmarks)
+ - cabal build
+
+ # tests that a source-distribution can be generated
+ - cabal sdist
+
+ # check that the generated source-distribution can be built & installed
+ - export SRC_TGZ=$(cabal info . | awk '{print $2 ".tar.gz";exit}') ;
+   cd dist/;
+   if [ -f "$SRC_TGZ" ]; then
+      cabal install --force-reinstalls "$SRC_TGZ";
+   else
+      echo "expected '$SRC_TGZ' not found";
+      exit 1;
+   fi
 
 notifications:
   irc:
diff --git a/CHANGELOG.markdown b/CHANGELOG.markdown
--- a/CHANGELOG.markdown
+++ b/CHANGELOG.markdown
@@ -1,3 +1,9 @@
+0.2.1.1
+-------
+* Minor documentation improvements.
+* Require `base >= 4.7` properly in the source repository as the implementation uses `coerce`, so it doesn't work on GHC < 7.8.
+  This was fixed by maintenance releases to hackage previously.
+
 0.2.1
 -----
 * Fixed bug in `signum`
diff --git a/LICENSE b/LICENSE
--- a/LICENSE
+++ b/LICENSE
@@ -1,4 +1,4 @@
-Copyright 2014 Edward Kmett
+Copyright 2014-2015 Edward Kmett
 
 All rights reserved.
 
diff --git a/fixed.cabal b/fixed.cabal
--- a/fixed.cabal
+++ b/fixed.cabal
@@ -1,6 +1,6 @@
 name:          fixed
 category:      Numeric
-version:       0.2.1
+version:       0.2.1.1
 license:       BSD3
 cabal-version: >= 1.8
 license-file:  LICENSE
@@ -27,6 +27,6 @@
 
 library
   hs-source-dirs: src
-  build-depends: base >= 4 && < 5
+  build-depends: base >= 4.7 && < 5
   ghc-options: -Wall -fwarn-tabs -O2
   exposed-modules: Numeric.Fixed
diff --git a/src/Numeric/Fixed.hs b/src/Numeric/Fixed.hs
--- a/src/Numeric/Fixed.hs
+++ b/src/Numeric/Fixed.hs
@@ -1,4 +1,18 @@
 {-# LANGUAGE CApiFFI, DeriveDataTypeable, GeneralizedNewtypeDeriving #-}
+-----------------------------------------------------------------------------
+-- |
+-- Copyright   :  (C) 2014-15 Edward Kmett
+-- License     :  BSD-style (see the file LICENSE)
+-- Maintainer  :  Edward Kmett <ekmett@gmail.com>
+-- Stability   :  experimental
+-- Portability :  non-portable
+--
+-- Fixed precision arithmetic. This format is the same format used by
+-- OpenGL ES 1's @GLfixed@ data type:
+--
+-- One sign bit, 15 bits to the left of the decimal place and 16 bits
+-- to the right packed into a 32-bit integer.
+-----------------------------------------------------------------------------
 module Numeric.Fixed 
   ( Fixed(..)
   , fromFixed
@@ -16,9 +30,11 @@
 -- | A signed 2s complement 15.16 scale fixed precision number
 newtype {-# CTYPE "signed int" #-} Fixed = Fixed { getFixed :: CInt } deriving (Eq,Ord,Typeable,Storable)
 
+-- | Convert from a 'Fixed' precision value to a 'Double'
 fromFixed :: Fixed -> Double
 fromFixed (Fixed x) = fromIntegral x / 65536
 
+-- | Convert from a 'Double' to a 'Fixed' precision value
 toFixed :: Double -> Fixed
 toFixed x = Fixed $ floor (x * 65536 + 0.5)