diff --git a/.circleci/config.yml b/.circleci/config.yml
index 88213c26..011fe56d 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -25,10 +25,35 @@ jobs:
       - checkout
       - run: COMPOSER=composer.circleci.json composer install
       - run: COMPOSER=composer.circleci.json composer test
+  build_php5.4:
+    docker:
+      - image: lavoweb/php-5.4
+    steps:
+      - run:
+          name: PHP version check
+          command: php --version
+      - run:
+          name: Install system packages
+          command: apt-get update && apt-get -y install git
+      - checkout
+      - run:
+          name: Install composer
+          command: |
+            php -r "copy('https://getcomposer.org/installer', 'composer-setup.php');"
+            php -r "if (hash_file('SHA384', 'composer-setup.php') === trim(file_get_contents('https://composer.github.io/installer.sig'))) { echo 'Installer verified'; } else { echo 'Installer invalid'; unlink('composer-setup.php'); } echo PHP_EOL;"
+            php composer-setup.php
+            php -r "unlink('composer-setup.php');"
+      - run:
+          name: Install dependencies
+          command: COMPOSER=composer.circleci.json php composer.phar install
+      - run:
+          name: Run tests
+          command: COMPOSER=composer.circleci.json php composer.phar test
 workflows:
   version: 2
   build_php_versions:
     jobs:
+      - build_php5.4
       - build_php5.6
       - build_php7.3
       - build_php7.4
diff --git a/README.md b/README.md
index 6b84793d..b62770a7 100644
--- a/README.md
+++ b/README.md
@@ -12,7 +12,7 @@ Plugin for PHP_CodeSniffer static analysis tool that adds analysis of problemati
 
 ### Requirements
 
-VariableAnalysis requires PHP 5.6 or higher and [PHP CodeSniffer](https://github.com/squizlabs/PHP_CodeSniffer) version 3.5.0 or higher.
+VariableAnalysis requires PHP 5.4 or higher and [PHP CodeSniffer](https://github.com/squizlabs/PHP_CodeSniffer) version 3.5.0 or higher.
 
 It also requires [PHPCSUtils](https://phpcsutils.com/) which must be installed as a PHPCS standard. If you are using composer, this will be done automatically (see below).
 
@@ -97,7 +97,7 @@ This was forked from the excellent work in https://github.com/illusori/PHP_Codes
 
 Please open issues or PRs on this repository.
 
-Any changes should be accompanied by tests and should pass linting and static analysis. Please use phpdoc (rather than actual types) for declaring types since this must run in PHP 5.6.
+Any changes should be accompanied by tests and should pass linting and static analysis. Please use phpdoc (rather than actual types) for declaring types since this must run in PHP 5.4.
 
 To run tests, make sure composer is installed, then run:
 
diff --git a/Tests/BaseTestCase.php b/Tests/BaseTestCase.php
index 5f4c9200..5f75523e 100644
--- a/Tests/BaseTestCase.php
+++ b/Tests/BaseTestCase.php
@@ -8,15 +8,16 @@
 
 class BaseTestCase extends TestCase {
   const STANDARD_NAME = 'VariableAnalysis';
-  const SNIFF_FILE = __DIR__ . '/../VariableAnalysis/Sniffs/CodeAnalysis/VariableAnalysisSniff.php';
 
   public function prepareLocalFileForSniffs($fixtureFile) {
+    $sniffFile = __DIR__ . '/../VariableAnalysis/Sniffs/CodeAnalysis/VariableAnalysisSniff.php';
+
     $config            = new Config();
     $config->cache     = false;
     $config->standards = [self::STANDARD_NAME];
     $config->ignored   = [];
 
-    $sniffFiles = [realpath(self::SNIFF_FILE)];
+    $sniffFiles = [realpath($sniffFile)];
     $ruleset    = new Ruleset($config);
     $ruleset->registerSniffs($sniffFiles, [], []);
     $ruleset->populateTokenListeners();
diff --git a/VariableAnalysis/Lib/Helpers.php b/VariableAnalysis/Lib/Helpers.php
index e50bf040..684b230d 100644
--- a/VariableAnalysis/Lib/Helpers.php
+++ b/VariableAnalysis/Lib/Helpers.php
@@ -487,7 +487,8 @@ public static function getVariablesDefinedByArrowFunction(File $phpcsFile, $stac
   /**
    * @return void
    */
-  public static function debug(...$messages) {
+  public static function debug() {
+    $messages = func_get_args();
     if (! defined('PHP_CODESNIFFER_VERBOSITY')) {
       return;
     }
diff --git a/composer.circleci.json b/composer.circleci.json
index dce6a631..066a5546 100644
--- a/composer.circleci.json
+++ b/composer.circleci.json
@@ -37,11 +37,11 @@
         "test": "./vendor/bin/phpunit --configuration phpunit.circleci.xml"
     },
     "require" : {
-        "php" : ">=5.6.0",
+        "php" : ">=5.4.0",
         "squizlabs/php_codesniffer": "^3.1",
         "phpcsstandards/phpcsutils": "^1.0"
     },
     "require-dev": {
-        "phpunit/phpunit": "^5.0 || ^6.5 || ^7.0 || ^8.0"
+        "phpunit/phpunit": "^4.0 || ^5.0 || ^6.5 || ^7.0 || ^8.0"
     }
 }
diff --git a/composer.json b/composer.json
index 64f53c1a..a0224240 100644
--- a/composer.json
+++ b/composer.json
@@ -39,7 +39,7 @@
         "phpstan": "./vendor/bin/phpstan analyse"
     },
     "require" : {
-        "php" : ">=5.6.0",
+        "php" : ">=5.4.0",
         "squizlabs/php_codesniffer": "^3.5",
         "phpcsstandards/phpcsutils": "^1.0"
     },