diff --git a/tests/Token/ClassTest.php b/tests/Token/ClassTest.php
index 05eca32..a12efa1 100644
--- a/tests/Token/ClassTest.php
+++ b/tests/Token/ClassTest.php
@@ -22,7 +22,7 @@ class PHP_Token_ClassTest extends TestCase
      */
     private $function;
 
-    protected function setUp()
+    protected function setUp(): void
     {
         foreach (new PHP_Token_Stream(TEST_FILES_PATH . 'source2.php') as $token) {
             if ($token instanceof PHP_Token_CLASS) {
diff --git a/tests/Token/ClosureTest.php b/tests/Token/ClosureTest.php
index 4e893d8..9654f00 100644
--- a/tests/Token/ClosureTest.php
+++ b/tests/Token/ClosureTest.php
@@ -17,7 +17,7 @@ class PHP_Token_ClosureTest extends TestCase
      */
     private $functions;
 
-    protected function setUp()
+    protected function setUp(): void
     {
         foreach (new PHP_Token_Stream(TEST_FILES_PATH . 'closure.php') as $token) {
             if ($token instanceof PHP_Token_FUNCTION) {
diff --git a/tests/Token/FunctionTest.php b/tests/Token/FunctionTest.php
index c88454b..81976d4 100644
--- a/tests/Token/FunctionTest.php
+++ b/tests/Token/FunctionTest.php
@@ -17,7 +17,7 @@ class PHP_Token_FunctionTest extends TestCase
      */
     private $functions;
 
-    protected function setUp()
+    protected function setUp(): void
     {
         foreach (new PHP_Token_Stream(TEST_FILES_PATH . 'source.php') as $token) {
             if ($token instanceof PHP_Token_FUNCTION) {
diff --git a/tests/Token/IncludeTest.php b/tests/Token/IncludeTest.php
index 7f83a73..97c7604 100644
--- a/tests/Token/IncludeTest.php
+++ b/tests/Token/IncludeTest.php
@@ -17,7 +17,7 @@ class PHP_Token_IncludeTest extends TestCase
      */
     private $ts;
 
-    protected function setUp()
+    protected function setUp(): void
     {
         $this->ts = new PHP_Token_Stream(TEST_FILES_PATH . 'source3.php');
     }
diff --git a/tests/Token/InterfaceTest.php b/tests/Token/InterfaceTest.php
index c61ec38..51200a4 100644
--- a/tests/Token/InterfaceTest.php
+++ b/tests/Token/InterfaceTest.php
@@ -22,7 +22,7 @@ class PHP_Token_InterfaceTest extends TestCase
      */
     private $interfaces;
 
-    protected function setUp()
+    protected function setUp(): void
     {
         $ts = new PHP_Token_Stream(TEST_FILES_PATH . 'source4.php');
         $i  = 0;