diff --git a/.travis.yml b/.travis.yml
index 3d40388..30f5fa2 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,3 +1,9 @@
-script: ./run_tests.sh
-before_script:
-  - sudo apt-get install zsh
+os:
+  - linux
+  - osx
+
+install:
+  - ./test/support/travisci_deps.sh
+
+script:
+  - ./run_tests.sh
diff --git a/test/support/travisci_deps.sh b/test/support/travisci_deps.sh
new file mode 100755
index 0000000..d4523ee
--- /dev/null
+++ b/test/support/travisci_deps.sh
@@ -0,0 +1,14 @@
+#!/usr/bin/env bash
+# Installs dependencies for travis-ci environments.
+
+# Install dependencies, which looks to be just bash & zsh.
+#
+# Darwin has zsh preinstalled already, so only need to install on Ubuntu.
+#
+# Note: $TRAVIS_OS_NAME will only be set on text boxes with multi-os enabled,
+# so use negation test so it will fail gracefully on normal Travis linux setup.
+#
+# TODO: also perhaps later only on ZSH test box if we split those
+if [[ "$TRAVIS_OS_NAME" != "osx" ]]; then
+  sudo apt-get install zsh
+fi