diff --git a/.travis.yml b/.travis.yml
index fd2c05b7..33148c36 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,4 +1,5 @@
 language: php
 php:
+  - '5.6'
   - '7.1'
 script: git diff --name-only $TRAVIS_COMMIT_RANGE | grep '\.php$' | xargs -n1 -P8 php -l | grep -v 'No syntax errors'; test $? -eq 1