diff --git a/.travis.yml b/.travis.yml
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,54 +1,96 @@
-language: haskell
+language: c
+sudo: false
 
-env:
-  - GHCVER=7.8.3
-  - GHCVER=head
+cache:
+  directories:
+    - $HOME/.cabsnap
+    - $HOME/.cabal/packages
 
+before_cache:
+  - rm -fv $HOME/.cabal/packages/hackage.haskell.org/build-reports.log
+  - rm -fv $HOME/.cabal/packages/hackage.haskell.org/00-index.tar
+
 matrix:
-  allow_failures:
-    - env: GHCVER=head
+  include:
+    - env: CABALVER=1.16 GHCVER=7.4.2
+      compiler: ": #GHC 7.4.2"
+      addons: {apt: {packages: [cabal-install-1.16,ghc-7.4.2,alex-3.1.4,happy-1.19.5], sources: [hvr-ghc]}}
+    - env: CABALVER=1.16 GHCVER=7.6.3
+      compiler: ": #GHC 7.6.3"
+      addons: {apt: {packages: [cabal-install-1.16,ghc-7.6.3,alex-3.1.4,happy-1.19.5], sources: [hvr-ghc]}}
+    - env: CABALVER=1.18 GHCVER=7.8.4
+      compiler: ": #GHC 7.8.4"
+      addons: {apt: {packages: [cabal-install-1.18,ghc-7.8.4,alex-3.1.4,happy-1.19.5], sources: [hvr-ghc]}}
+    - env: CABALVER=1.22 GHCVER=7.10.1
+      compiler: ": #GHC 7.10.1"
+      addons: {apt: {packages: [cabal-install-1.22,ghc-7.10.1,alex-3.1.4,happy-1.19.5], sources: [hvr-ghc]}}
+    - env: CABALVER=1.22 GHCVER=7.10.2
+      compiler: ": #GHC 7.10.2"
+      addons: {apt: {packages: [cabal-install-1.22,ghc-7.10.2,alex-3.1.4,happy-1.19.5], sources: [hvr-ghc]}}
 
 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:$PATH
-    fi
+ - unset CC
+ - export HAPPYVER=1.19.5
+ - export ALEXVER=3.1.4
+ - export PATH=~/.cabal/bin:/opt/ghc/$GHCVER/bin:/opt/cabal/$CABALVER/bin:/opt/happy/$HAPPYVER/bin:/opt/alex/$ALEXVER/bin:$PATH
 
 install:
-  - $CABAL install --dependencies-only --enable-tests
-  - $CABAL configure --enable-tests $MODE
+ - cabal --version
+ - echo "$(ghc --version) [$(ghc --print-project-git-commit-id 2> /dev/null || echo '?')]"
+ - if [ -f $HOME/.cabal/packages/hackage.haskell.org/00-index.tar.gz ];
+   then
+     zcat $HOME/.cabal/packages/hackage.haskell.org/00-index.tar.gz >
+          $HOME/.cabal/packages/hackage.haskell.org/00-index.tar;
+   fi
+ - travis_retry cabal update
+ - "sed -i  's/^jobs:.*$/jobs: 2/' $HOME/.cabal/config"
+ - cabal install --only-dependencies --enable-tests --enable-benchmarks --dry -v > installplan.txt
+ - sed -i -e '1,/^Resolving /d' installplan.txt; cat installplan.txt
 
+# check whether current requested install-plan matches cached package-db snapshot
+ - if diff -u installplan.txt $HOME/.cabsnap/installplan.txt;
+   then
+     echo "cabal build-cache HIT";
+     rm -rfv .ghc;
+     cp -a $HOME/.cabsnap/ghc $HOME/.ghc;
+     cp -a $HOME/.cabsnap/lib $HOME/.cabsnap/share $HOME/.cabsnap/bin $HOME/.cabal/;
+   else
+     echo "cabal build-cache MISS";
+     rm -rf $HOME/.cabsnap;
+     mkdir -p $HOME/.ghc $HOME/.cabal/lib $HOME/.cabal/share $HOME/.cabal/bin;
+     cabal install --only-dependencies --enable-tests --enable-benchmarks;
+     if [ "$GHCVER" = "7.10.1" ]; then cabal install Cabal-1.22.4.0; fi;
+   fi
+
+# snapshot package-db on cache miss
+ - if [ ! -d $HOME/.cabsnap ];
+   then
+      echo "snapshotting package-db to build-cache";
+      mkdir $HOME/.cabsnap;
+      cp -a $HOME/.ghc $HOME/.cabsnap/ghc;
+      cp -a $HOME/.cabal/lib $HOME/.cabal/share $HOME/.cabal/bin installplan.txt $HOME/.cabsnap/;
+   fi
+
+# 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
+ - cabal configure --enable-tests -v2  # -v2 provides useful information for debugging
+ - cabal build   # this builds all libraries and executables (including tests)
+ - cabal test
+ - cabal bench || true  # expected result: these will crash
+ - cabal sdist || true  # tests that a source-distribution can be generated
 
+# Check that the resulting source distribution can be built & installed.
+# If there are no other `.tar.gz` files in `dist`, this can be even simpler:
+# `cabal install --force-reinstalls dist/*-*.tar.gz`
+ - SRC_TGZ=$(cabal info . | awk '{print $2;exit}').tar.gz &&
+   (cd dist && cabal install --force-reinstalls "$SRC_TGZ")
+
 notifications:
   irc:
     channels:
       - "irc.freenode.org#haskell-lens"
     skip_join: true
     template:
-      - "\x0313half\x03/\x0306%{branch}\x03 \x0314%{commit}\x03 %{build_url} %{message}"
+      - "\x0313half\x0f/\x0306%{branch}\x0f \x0314%{commit}\x0f %{message} \x0302\x1f%{build_url}\x0f"
+# EOF
diff --git a/CHANGELOG.markdown b/CHANGELOG.markdown
--- a/CHANGELOG.markdown
+++ b/CHANGELOG.markdown
@@ -1,3 +1,8 @@
+0.2.2
+-----
+* Fixed `isInfinite`.
+* Added support for older GHCs. On GHC < 7.8 the pattern synonyms are disabled.
+
 0.2.1
 -----
 * Removed need for `GeneralizedNewtypeDeriving` and `ScopedTypeVariables`.
diff --git a/half.cabal b/half.cabal
--- a/half.cabal
+++ b/half.cabal
@@ -1,6 +1,6 @@
 name:          half
 category:      Numeric
-version:       0.2.1
+version:       0.2.2
 license:       BSD3
 cabal-version: >= 1.8
 license-file:  LICENSE
diff --git a/src/Numeric/Half.hs b/src/Numeric/Half.hs
--- a/src/Numeric/Half.hs
+++ b/src/Numeric/Half.hs
@@ -1,6 +1,9 @@
-{-# LANGUAGE ForeignFunctionInterface #-}
+{-# LANGUAGE CPP #-}
+#if __GLASGOW_HASKELL__ >= 708
 {-# LANGUAGE PatternSynonyms #-}
+#endif
 {-# LANGUAGE DeriveDataTypeable #-}
+{-# LANGUAGE ForeignFunctionInterface #-}
 -----------------------------------------------------------------------------
 -- |
 -- Copyright   :  (C) 2014 Edward Kmett
@@ -19,6 +22,7 @@
   , isZero
   , fromHalf
   , toHalf
+#if __GLASGOW_HASKELL__ >= 708
   , pattern POS_INF
   , pattern NEG_INF
   , pattern QNaN
@@ -30,6 +34,7 @@
   , pattern HALF_DIG
   , pattern HALF_MIN_10_EXP
   , pattern HALF_MAX_10_EXP
+#endif
   ) where
 
 import Data.Bits
@@ -108,7 +113,7 @@
   floatRadix  _ = 2
   floatDigits _ = 11
   decodeFloat = decodeFloat . fromHalf
-  isInfinite (Half h) = unsafeShiftR h 10 .&. 0x1f >= 32
+  isInfinite (Half h) = unsafeShiftR h 10 .&. 0x1f >= 31
   isIEEE _ = isIEEE (undefined :: Float)
   atan2 a b = toHalf $ atan2 (fromHalf a) (fromHalf b)
   isDenormalized (Half h) = unsafeShiftR h 10 .&. 0x1f == 0 && h .&. 0x3ff /= 0
@@ -124,6 +129,8 @@
 isZero :: Half -> Bool
 isZero (Half h) = h .&. 0x7fff == 0
 
+#if __GLASGOW_HASKELL__ >= 708
+
 -- | Positive infinity
 pattern POS_INF = Half 0x7c00
 
@@ -156,6 +163,8 @@
 
 -- Maximum positive integer such that 10 raised to that power is a normalized half
 pattern HALF_MAX_10_EXP = 4
+
+#endif
 
 instance Num Half where
   a * b = toHalf (fromHalf a * fromHalf b)