diff --git a/.travis.yml b/.travis.yml
index 9d0700d3a84..fc4f8bb4506 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -121,19 +121,24 @@ install:
 
 - |
   echo "Installing Composer dependencies - PHP Unit, Parallel Lint, PHP CodeSniffer - for $TRAVIS_PHP_VERSION"
-  if [ "$TRAVIS_PHP_VERSION" = '5.6' ] || [ "$TRAVIS_PHP_VERSION" = '7.0' ] || [ "$TRAVIS_PHP_VERSION" = '7.1' ] \
-     [ "$TRAVIS_PHP_VERSION" = '7.2' ] || [ "$TRAVIS_PHP_VERSION" = '7.3' ] || [ "$TRAVIS_PHP_VERSION" = '7.4' ]; then
+  if [ "$TRAVIS_PHP_VERSION" = '5.6' ] || [ "$TRAVIS_PHP_VERSION" = '7.0' ] || [ "$TRAVIS_PHP_VERSION" = '7.1' ] || [ "$TRAVIS_PHP_VERSION" = '7.2' ]; then
     composer -n require phpunit/phpunit ^5 \
                         php-parallel-lint/php-parallel-lint ^1 \
                         php-parallel-lint/php-console-highlighter ^0 \
                         squizlabs/php_codesniffer ^3
   fi
+  if [ "$TRAVIS_PHP_VERSION" = '7.3' ] || [ "$TRAVIS_PHP_VERSION" = '7.4' ]; then
+    composer -n require phpunit/phpunit ^9 \
+                        php-parallel-lint/php-parallel-lint ^1.2 \
+                        php-parallel-lint/php-console-highlighter ^0 \
+                        squizlabs/php_codesniffer ^3
+  fi
   if [ "$TRAVIS_PHP_VERSION" = 'nightly' ]; then
-      composer -n require --ignore-platform-reqs phpunit/phpunit ^5 \
+      composer -n require --ignore-platform-reqs phpunit/phpunit ^9 \
                                                  php-parallel-lint/php-parallel-lint ^1.2 \
                                                  php-parallel-lint/php-console-highlighter ^0 \
                                                  squizlabs/php_codesniffer ^3
-    fi
+  fi
   echo
 
 - |
diff --git a/test/test_serialize.php b/test/other/test_serialize.php
similarity index 100%
rename from test/test_serialize.php
rename to test/other/test_serialize.php