diff --git a/.travis.yml b/.travis.yml
index e034df2d5b3f6b8586f82e25bb5a7a347795913c..f5ea84384cca2b755e123dc1903e13e86069b11b 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -20,28 +20,44 @@ env:
 jobs:
   include:
     - dist: bionic
-      env: BUILDTYPE=Release
+      env: 
+        - BUILDTYPE=Release
+        - TRAVIS_PYTHON_VERSION=27 
       python: 2.7
     - dist: bionic
-      env: BUILDTYPE=Release
+      env: 
+        - BUILDTYPE=Release
+        - TRAVIS_PYTHON_VERSION=36
       python: 3.6
     - dist: bionic
-      env: BUILDTYPE=Debug
+      env: 
+        - BUILDTYPE=Debug
+        - TRAVIS_PYTHON_VERSION=27 
       python: 2.7
     - dist: bionic
-      env: BUILDTYPE=Debug
+      env: 
+        - BUILDTYPE=Debug
+        - TRAVIS_PYTHON_VERSION=36
       python: 3.6
     - dist: xenial
-      env: BUILDTYPE=Release
+      env: 
+        - BUILDTYPE=Release
+        - TRAVIS_PYTHON_VERSION=27 
       python: 2.7
     - dist: xenial
-      env: BUILDTYPE=Release
+      env: 
+        - BUILDTYPE=Release
+        - TRAVIS_PYTHON_VERSION=35 
       python: 3.5
     - dist: trusty 
-      env: BUILDTYPE=Release
+      env: 
+        - BUILDTYPE=Release
+        - TRAVIS_PYTHON_VERSION=27 
       python: 2.7
     - dist: trusty 
-      env: BUILDTYPE=Release
+      env: 
+        - BUILDTYPE=Release
+        - TRAVIS_PYTHON_VERSION=34
       python: 3.4
 
 notifications:
diff --git a/travis_custom/custom_build b/travis_custom/custom_build
index 3c7d80ecdf63b723e0ce4ee8d06f2c18db0fdf9f..1351351619862f8d005b8ddad44d74b264666703 100755
--- a/travis_custom/custom_build
+++ b/travis_custom/custom_build
@@ -2,13 +2,17 @@
 set -e
 
 # Setup environment variables.
-export CMAKE_ADDITIONAL_OPTIONS=" ${CMAKE_ADDITIONAL_OPTIONS} -DBUILD_BENCHMARK=\"ON\" -DBUILD_UNIT_TESTS=\"ON\" -DCMAKE_CXX_FLAGS=-DBOOST_SYSTEM_NO_DEPRECATED -DPYTHON_EXECUTABLE=$(which python)"
+export CMAKE_ADDITIONAL_OPTIONS=" ${CMAKE_ADDITIONAL_OPTIONS} -DBUILD_BENCHMARK=\"ON\" -DBUILD_UNIT_TESTS=\"ON\" -DCMAKE_CXX_FLAGS=-DBOOST_SYSTEM_NO_DEPRECATED"
 if [[ ";${DO_INSTALL_DOC_EXCEPT_ON_BRANCH};" == *";${CI_BRANCH};"* ]]; then
   export CMAKE_ADDITIONAL_OPTIONS=" ${CMAKE_ADDITIONAL_OPTIONS} -DINSTALL_DOCUMENTATION=\"OFF\""
 else
   export CMAKE_ADDITIONAL_OPTIONS=" ${CMAKE_ADDITIONAL_OPTIONS} -DINSTALL_DOCUMENTATION=\"ON\""
 fi
 
+if [[ $TRAVIS_PYTHON_VERSION -gt 30 ]]; then
+  export CMAKE_ADDITIONAL_OPTIONS=" ${CMAKE_ADDITIONAL_OPTIONS} -DPYTHON_EXECUTABLE=$(which python3)"
+fi
+
 # Setup environment variables.
 . ./.travis/run ../.travis/build