diff --git a/.travis.yml b/.travis.yml
index d8746c0..a9bbd44 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,6 +1,6 @@
 language: cpp
 
-dist: trusty # default distribution
+dist: xenial # default distribution
 os: linux # default os
 sudo: false
 
@@ -8,29 +8,35 @@ sudo: false
 matrix:
   fast_finish: true
   include:
-    - env: VERBOSE=1 E_CC=gcc-5 E_CXX=g++-5 GENERATOR="Unix Makefiles"
+    - env: MATRIX_EVAL="CC=gcc-5 && CXX=g++-5 && GENERATOR='Unix Makefiles'"
       addons: { apt: { packages: ["g++-5"], sources: ["ubuntu-toolchain-r-test"] } }
 
-    - env: E_CC=gcc-6 E_CXX=g++-6 GENERATOR="Unix Makefiles"
+    - env: MATRIX_EVAL="CC=gcc-6 && CXX=g++-6 && GENERATOR='Unix Makefiles'"
       addons: { apt: { packages: ["g++-6"], sources: ["ubuntu-toolchain-r-test"] } }
 
-    - env: E_CC=gcc-7 E_CXX=g++-7 GENERATOR="Unix Makefiles"
+    - env: MATRIX_EVAL="CC=gcc-7 && CXX=g++-7 && GENERATOR='Unix Makefiles'"
       addons: { apt: { packages: ["g++-7"], sources: ["ubuntu-toolchain-r-test"] } }
 
-    - env: E_CC=gcc-8 E_CXX=g++-8 GENERATOR="Unix Makefiles"
+    - env: MATRIX_EVAL="CC=gcc-8 && CXX=g++-8 && GENERATOR='Unix Makefiles'"
       addons: { apt: { packages: ["g++-8"], sources: ["ubuntu-toolchain-r-test"] } }
 
-    - env: E_CC=clang-5.0 E_CXX=clang++-5.0 GENERATOR="Unix Makefiles"
-      addons: { apt: { packages: ["g++-8", "clang-5.0"], sources: ["llvm-toolchain-trusty-5.0", "ubuntu-toolchain-r-test"] } }
+    - env: MATRIX_EVAL="CC=clang-5.0 && CXX=clang++-5.0 && GENERATOR='Unix Makefiles'"
+      addons: { apt: { packages: ["clang-5.0"], sources: ["ubuntu-toolchain-r-test"] } }
 
-    - env: E_CC=clang-6.0 E_CXX=clang++-6.0 GENERATOR="Unix Makefiles"
-      addons: { apt: { packages: ["g++-8", "clang-6.0"], sources: ["llvm-toolchain-trusty-6.0", "ubuntu-toolchain-r-test"] } }
+    - env: MATRIX_EVAL="CC=clang-6.0 && CXX=clang++-6.0 && GENERATOR='Unix Makefiles'"
+      addons: { apt: { packages: ["clang-6.0"], sources: ["ubuntu-toolchain-r-test"] } }
 
     - os: osx
-      env: E_CC=clang E_CXX=clang++ GENERATOR="Xcode"
+      env: MATRIX_EVAL="CC=clang && CXX=clang++ && GENERATOR=Xcode"
       osx_image: xcode9.2
   
 install:
+  - eval "${MATRIX_EVAL}"
+  - |
+    if [ "${TRAVIS_OS_NAME}" = "osx" ]; then
+      brew update
+      brew upgrade cmake
+    fi
   - $CC --version
   - $CXX --version
   - cmake --version
@@ -39,7 +45,7 @@ before_script:
   - mkdir build
   - cd build
   - export VERBOSE=1
-  - cmake -G"${GENERATOR}" -DCMAKE_CXX_COMPILER=${E_CXX} -DCMAKE_C_COMPILER=${E_CC} ..
+  - cmake -G"${GENERATOR}" -DCMAKE_CXX_COMPILER=${CXX} -DCMAKE_C_COMPILER=${CC} ..
 
 script:
   - export VERBOSE=1