diff --git a/.travis.yml b/.travis.yml
index efeef104fc..99479ca595 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -31,13 +31,22 @@ before_script:
        yes "" | pecl install igbinary;
        echo "extension=memcached.so" >> ~/.phpenv/versions/$(phpenv version-name)/etc/php.ini;
        phpenv config-rm xdebug.ini;
-       composer require 'phpunit/phpunit:~5.7';
        ;;
     "7"|"7.0"|"7.1"|"7.2"|"7.3"|"master")
        yes "" | pecl install apcu;
        echo "extension=memcached.so" >> ~/.phpenv/versions/$(phpenv version-name)/etc/php.ini;
        phpenv config-rm xdebug.ini;
-       composer require 'phpunit/phpunit:~6.3';
+      ;;
+    esac
+  - case $(phpenv version-name) in
+    "5.6")
+       composer require 'phpunit/phpunit:~5.7';
+       ;;
+    "7")
+       composer require 'phpunit/phpunit:~6';
+       ;;
+    *)
+       composer require 'phpunit/phpunit:~7';
       ;;
     esac
   #- php -m