diff --git a/Classes/Annotations/ReadOnly.php b/Classes/Annotations/ReadOnly.php
index cac72be..24cc7db 100644
--- a/Classes/Annotations/ReadOnly.php
+++ b/Classes/Annotations/ReadOnly.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace DigiComp\FlowSessionLock\Annotations;
 
 /**
diff --git a/Classes/Aspects/ReadOnlyAspect.php b/Classes/Aspects/ReadOnlyAspect.php
index 355ddf4..3ece8df 100644
--- a/Classes/Aspects/ReadOnlyAspect.php
+++ b/Classes/Aspects/ReadOnlyAspect.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace DigiComp\FlowSessionLock\Aspects;
 
 use DigiComp\FlowSessionLock\Http\SessionLockRequestComponent;
diff --git a/Classes/Aspects/ReadOnlyFilter.php b/Classes/Aspects/ReadOnlyFilter.php
index 4925d4c..751ea6e 100644
--- a/Classes/Aspects/ReadOnlyFilter.php
+++ b/Classes/Aspects/ReadOnlyFilter.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace DigiComp\FlowSessionLock\Aspects;
 
 use Neos\Flow\Annotations as Flow;
diff --git a/Classes/Http/SessionLockRequestComponent.php b/Classes/Http/SessionLockRequestComponent.php
index 691c95b..aa0b45e 100644
--- a/Classes/Http/SessionLockRequestComponent.php
+++ b/Classes/Http/SessionLockRequestComponent.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace DigiComp\FlowSessionLock\Http;
 
 use Neos\Flow\Annotations as Flow;