diff --git a/.travis.yml b/.travis.yml
index 2eacc17..ea1a3af 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -15,12 +15,12 @@ addons:
       - devscripts
 before_install:
   # OS X: install the checkbashisms script
-  - test "$TRAVIS_OS_NAME" = osx && brew update
-  - test "$TRAVIS_OS_NAME" = osx && brew install checkbashisms
+  - test "$TRAVIS_OS_NAME" = osx && brew update || true
+  - test "$TRAVIS_OS_NAME" = osx && brew install checkbashisms || true
 
 script:
   # Run some code checkings on the script itself
-  - checkbashisms clitest
+  - checkbashisms --posix clitest
   # Run the full test suite in all the supported POSIX shells
   - bash clitest test.md
   - ksh  clitest test.md