diff --git a/Tests/EventListener/ErrorListenerTest.php b/Tests/EventListener/ErrorListenerTest.php
index 6ad89dc52..40020baee 100644
--- a/Tests/EventListener/ErrorListenerTest.php
+++ b/Tests/EventListener/ErrorListenerTest.php
@@ -140,7 +140,7 @@ public function getParameterOption($values, $default = false, $onlyParams = fals
     {
     }
 
-    public function parse()
+    public function parse(): void
     {
     }
 
diff --git a/Tests/Output/OutputTest.php b/Tests/Output/OutputTest.php
index f337c4ddd..b7c0a98d9 100644
--- a/Tests/Output/OutputTest.php
+++ b/Tests/Output/OutputTest.php
@@ -182,7 +182,7 @@ public function clear()
         $this->output = '';
     }
 
-    protected function doWrite(string $message, bool $newline)
+    protected function doWrite(string $message, bool $newline): void
     {
         $this->output .= $message.($newline ? "\n" : '');
     }
diff --git a/Tests/TerminalTest.php b/Tests/TerminalTest.php
index d8af7dc1f..653dd4afc 100644
--- a/Tests/TerminalTest.php
+++ b/Tests/TerminalTest.php
@@ -41,7 +41,7 @@ private function resetStatics()
     {
         foreach (['height', 'width', 'stty'] as $name) {
             $property = new \ReflectionProperty(Terminal::class, $name);
-            $property->setValue(null);
+            $property->setValue(null, null);
         }
     }