diff --git a/lib/codegen/meta-python/check.sh b/lib/codegen/meta-python/check.sh
index 665e74fc33..fec63798df 100755
--- a/lib/codegen/meta-python/check.sh
+++ b/lib/codegen/meta-python/check.sh
@@ -19,7 +19,7 @@ runif flake8 .
 # Type checking.
 # TODO: Re-enable mypy on Travis osx. Pip currently installs mypy into a
 # directory which is not in the PATH.
-if [ "$TRAVIS_OS_NAME" != "osx" ]; then
+if [ "${TRAVIS_OS_NAME:-other}" != "osx" ]; then
     runif mypy --py2 build.py
 fi