diff --git a/.travis.yml b/.travis.yml
index 17e52dc..bc2f45e 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -2,13 +2,30 @@
 # http://about.travis-ci.org/docs/user/build-configuration/
 # This file can be validated on:
 # http://lint.travis-ci.org/
+# See also
+# http://stackoverflow.com/questions/22111549/travis-ci-with-clang-3-4-and-c11/30925448#30925448
+# to allow C++11, though we are not yet building with -std=c++11
 
-#before_install: sudo apt-get install -y cmake
-# cmake is pre-installed in Travis for both linux and osx
-
-before_install:
-  - sudo apt-get update -qq
-  - sudo apt-get install -qq valgrind
+install:
+# /usr/bin/gcc is 4.6 always, but gcc-X.Y is available.
+#- if [ "$CXX" = "g++" ]; then export CXX="g++-4.8" CC="gcc-4.8"; fi
+- if [ "$CXX" = "g++" ]; then export CXX="g++-4.6" CC="gcc-4.6"; fi
+# /usr/bin/clang is our version already, and clang-X.Y does not exist.
+#- if [ "$CXX" = "clang++" ]; then export CXX="clang++-3.3" CC="clang-3.3"; fi
+- echo ${PATH}
+- ls /usr/local
+- export PATH=/usr/bin:${PATH}
+- echo ${CXX}
+- ${CXX} --version
+addons:
+  apt:
+    sources:
+    - ubuntu-toolchain-r-test
+    packages:
+    - gcc-4.6
+    - g++-4.6
+    - clang-3.3
+    - valgrind
 os:
   - linux
 language: cpp
@@ -23,3 +40,4 @@ env:
 notifications:
   email:
     - aaronjjacobs@gmail.com
+sudo: false