diff --git a/composer.json b/composer.json
index 4c255e3..965f22b 100644
--- a/composer.json
+++ b/composer.json
@@ -22,8 +22,8 @@
     "require": {},
     "require-dev": {
         "friendsofphp/php-cs-fixer": "^2.0",
-        "phpunit/phpunit": "^5.7",
-        "symfony/var-dumper": "^3.2"
+        "phpunit/phpunit": "^7.5",
+        "symfony/var-dumper": "4.3"
     },
     "scripts": {
         "test": "phpunit",
diff --git a/phpunit.xml.dist b/phpunit.xml.dist
index 755a5f3..19dd55e 100644
--- a/phpunit.xml.dist
+++ b/phpunit.xml.dist
@@ -7,8 +7,7 @@
          convertNoticesToExceptions="true"
          convertWarningsToExceptions="true"
          processIsolation="false"
-         stopOnFailure="false"
-         syntaxCheck="false">
+         stopOnFailure="false">
     <testsuites>
         <testsuite name="Application Test Suite">
             <directory>tests</directory>
diff --git a/src/SnapshotAssertions.php b/src/SnapshotAssertions.php
index 4577282..d08f812 100644
--- a/src/SnapshotAssertions.php
+++ b/src/SnapshotAssertions.php
@@ -13,9 +13,9 @@ trait SnapshotAssertions
      *
      * @param mixed       $expected
      * @param string|null $identifier An additional identifier to append to the snapshot ID
-     * @param string|null $message    A message to throw in case of error
+     * @param string $message    A message to throw in case of error
      */
-    protected function assertEqualsSnapshot($expected, $identifier = null, $message = null)
+    protected function assertEqualsSnapshot($expected, $identifier = null, $message = '')
     {
         SnapshotsManager::setSuite($this);
         $snapshot = SnapshotsManager::upsertSnapshotContents($identifier, $expected);
diff --git a/tests/TestCase.php b/tests/TestCase.php
index 5b4b757..58beed1 100644
--- a/tests/TestCase.php
+++ b/tests/TestCase.php
@@ -2,9 +2,9 @@
 
 namespace Madewithlove\PhpunitSnapshots;
 
-use PHPUnit_Framework_TestCase;
+use PHPUnit\Framework\TestCase as PHPUnitFrameworkTestCase;
 
-abstract class TestCase extends PHPUnit_Framework_TestCase
+abstract class TestCase extends PHPUnitFrameworkTestCase
 {
     use SnapshotAssertions;
 }