diff --git a/lib/php/test/Unit/BinarySerializerTest.php b/lib/php/test/Unit/BinarySerializerTest.php
index b97da74..744ca7a 100644
--- a/lib/php/test/Unit/BinarySerializerTest.php
+++ b/lib/php/test/Unit/BinarySerializerTest.php
@@ -31,7 +31,7 @@
  */
 class BinarySerializerTest extends TestCase
 {
-    public function setUp()
+    public function setUp(): void
     {
         $loader = new ThriftClassLoader();
         $loader->registerNamespace('ThriftTest', __DIR__ . '/../Resources/packages/php');
diff --git a/lib/php/test/Unit/JsonSerializeTest.php b/lib/php/test/Unit/JsonSerializeTest.php
index 9fdc3f3..66e4d5e 100644
--- a/lib/php/test/Unit/JsonSerializeTest.php
+++ b/lib/php/test/Unit/JsonSerializeTest.php
@@ -31,7 +31,7 @@
  */
 class JsonSerializeTest extends TestCase
 {
-    protected function setUp()
+    protected function setUp(): void
     {
         $loader = new ThriftClassLoader();
         $loader->registerNamespace('ThriftTest', __DIR__ . '/../Resources/packages/phpjs');
diff --git a/lib/php/test/Unit/TJSONProtocolTest.php b/lib/php/test/Unit/TJSONProtocolTest.php
index 178d63b..9837803 100644
--- a/lib/php/test/Unit/TJSONProtocolTest.php
+++ b/lib/php/test/Unit/TJSONProtocolTest.php
@@ -37,7 +37,7 @@
     private $transport;
     private $protocol;
 
-    public static function setUpBeforeClass()
+    public static function setUpBeforeClass(): void
     {
         $loader = new ThriftClassLoader();
         $loader->registerNamespace('ThriftTest', __DIR__ . '/../Resources/packages/php');
@@ -48,7 +48,7 @@
         TJSONProtocolFixtures::populateTestArgsJSON();
     }
 
-    public function setUp()
+    public function setUp(): void
     {
         $this->transport = new TMemoryBuffer();
         $this->protocol = new TJSONProtocol($this->transport);
diff --git a/lib/php/test/Unit/TSimpleJSONProtocolTest.php b/lib/php/test/Unit/TSimpleJSONProtocolTest.php
index 3189d99..8e6a6d9 100644
--- a/lib/php/test/Unit/TSimpleJSONProtocolTest.php
+++ b/lib/php/test/Unit/TSimpleJSONProtocolTest.php
@@ -37,7 +37,7 @@
     private $transport;
     private $protocol;
 
-    public static function setUpBeforeClass()
+    public static function setUpBeforeClass(): void
     {
         $loader = new ThriftClassLoader();
         $loader->registerNamespace('ThriftTest', __DIR__ . '/../Resources/packages/php');
@@ -48,7 +48,7 @@
         TSimpleJSONProtocolFixtures::populateTestArgsSimpleJSON();
     }
 
-    public function setUp()
+    public function setUp(): void
     {
         $this->transport = new TMemoryBuffer();
         $this->protocol = new TSimpleJSONProtocol($this->transport);
diff --git a/lib/php/test/Unit/ValidatorTest.php b/lib/php/test/Unit/ValidatorTest.php
index 06f6e55..b125424 100644
--- a/lib/php/test/Unit/ValidatorTest.php
+++ b/lib/php/test/Unit/ValidatorTest.php
@@ -29,7 +29,7 @@
  */
 class ValidatorTest extends BaseValidatorTest
 {
-    public function setUp()
+    public function setUp(): void
     {
         $loader = new ThriftClassLoader();
         $loader->registerNamespace('ThriftTest', __DIR__ . '/../Resources/packages/phpv');
diff --git a/lib/php/test/Unit/ValidatorTestOop.php b/lib/php/test/Unit/ValidatorTestOop.php
index 79da11e..9558182 100644
--- a/lib/php/test/Unit/ValidatorTestOop.php
+++ b/lib/php/test/Unit/ValidatorTestOop.php
@@ -29,7 +29,7 @@
  */
 class ValidatorTestOop extends BaseValidatorTest
 {
-    public function setUp()
+    public function setUp(): void
     {
         $loader = new ThriftClassLoader();
         $loader->registerNamespace('ThriftTest', __DIR__ . '/../Resources/packages/phpvo');