diff --git a/.travis.yml b/.travis.yml
index b4ce771d8a8bbec727d27cbcca9091f331dfbd8f..897ed299b93863eca62e1ee8fd2ddd5e9db7d6e8 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -20,11 +20,15 @@ compiler:
     - gcc
     - clang
 
+before_install:
+    - if [[ "$TRAVIS_OS_NAME" == "osx" ]]; then brew update                         ; fi
+    - if [[ "$TRAVIS_OS_NAME" == "osx" ]]; then brew install homebrew/science/geant4; fi
+
 before_script:
     - $CC --version
     - mkdir build install rundir
     - cd build
-    - cmake .. -DBUILD_FAT=ON -DBUILD_WITHG4=OFF -DCMAKE_BUILD_TYPE=${BUILD} -DCMAKE_INSTALL_PREFIX=../install/
+    - cmake .. -DBUILD_FAT=ON -DCMAKE_BUILD_TYPE=${BUILD} -DCMAKE_INSTALL_PREFIX=../install/
 
 script:
     - make install