diff --git a/.travis.yml b/.travis.yml
index 6fde9c4a..12d5e15e 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -8,10 +8,24 @@ _native_job: &native_job
 
 language: shell
 
+os: linux
+
+dist: xenial
+
 jobs:
   - <<: *native_job
-    name: default Ubuntu
-    os: linux
+    name: Ubuntu 16.04
+  
   - <<: *native_job
-    name: MacOS
+    name: Ubuntu 18.04
+    dist: bionic
+    
+  - <<: *native_job
+    name: MacOS xcode9.4
     os: osx
+    osx_image: xcode9.4 # Default xcode on Travis.
+    
+  - <<: *native_job
+    name: MacOS xcode11.5
+    os: osx
+    osx_image: xcode11.5 # Latest xcode on Travis.