diff --git a/.travis.yml b/.travis.yml
index 0373ca3fe..424465ebf 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -168,7 +168,7 @@ script:
   - if [ `which valgrind` ]; then
     valgrind --error-exitcode=1 --leak-check=full ./json_unit ;
     fi
-  - if [ $os="osx" ]; then
+  - if [ $TRAVIS_OS_NAME="osx" ]; then
     brew tap nlohmann/json ;
     brew install nlohmann_json --HEAD ;
     brew test nlohmann_json ;