diff --git a/tests/Application/src/Conference/Form/SpeakerType.php b/tests/Application/src/Conference/Form/SpeakerType.php
index cf8f2e758..c5fe89b9a 100644
--- a/tests/Application/src/Conference/Form/SpeakerType.php
+++ b/tests/Application/src/Conference/Form/SpeakerType.php
@@ -20,7 +20,7 @@
 
 final class SpeakerType extends AbstractType
 {
-    public function buildForm(FormBuilderInterface $builder, array $options)
+    public function buildForm(FormBuilderInterface $builder, array $options): void
     {
         $builder
             ->add('firstName')
@@ -28,7 +28,7 @@ public function buildForm(FormBuilderInterface $builder, array $options)
         ;
     }
 
-    public function configureOptions(OptionsResolver $resolver)
+    public function configureOptions(OptionsResolver $resolver): void
     {
         $resolver->setDefaults([
             'data_class' => Speaker::class,
diff --git a/tests/Application/src/Form/Type/AuthorType.php b/tests/Application/src/Form/Type/AuthorType.php
index de97d56d2..4d1875b41 100644
--- a/tests/Application/src/Form/Type/AuthorType.php
+++ b/tests/Application/src/Form/Type/AuthorType.php
@@ -29,7 +29,7 @@ public function buildForm(FormBuilderInterface $builder, array $options): void
         ;
     }
 
-    public function configureOptions(OptionsResolver $resolver)
+    public function configureOptions(OptionsResolver $resolver): void
     {
         $resolver->setDefault('data_class', Author::class);
         $resolver->setDefault('validation_groups', ['sylius']);
diff --git a/tests/Application/src/Form/Type/BookTranslationType.php b/tests/Application/src/Form/Type/BookTranslationType.php
index dfbcc9612..1f239b050 100644
--- a/tests/Application/src/Form/Type/BookTranslationType.php
+++ b/tests/Application/src/Form/Type/BookTranslationType.php
@@ -19,12 +19,12 @@
 
 final class BookTranslationType extends AbstractResourceType
 {
-    public function buildForm(FormBuilderInterface $builder, array $options)
+    public function buildForm(FormBuilderInterface $builder, array $options): void
     {
         $builder->add('title', TextType::class);
     }
 
-    public function getBlockPrefix()
+    public function getBlockPrefix(): string
     {
         return 'app_book_translation';
     }
diff --git a/tests/Application/src/Form/Type/BookType.php b/tests/Application/src/Form/Type/BookType.php
index f002fe1c9..e90abbf27 100644
--- a/tests/Application/src/Form/Type/BookType.php
+++ b/tests/Application/src/Form/Type/BookType.php
@@ -20,7 +20,7 @@
 
 final class BookType extends AbstractResourceType
 {
-    public function buildForm(FormBuilderInterface $builder, array $options)
+    public function buildForm(FormBuilderInterface $builder, array $options): void
     {
         $builder
             ->add('translations', ResourceTranslationsType::class, [
@@ -31,7 +31,7 @@ public function buildForm(FormBuilderInterface $builder, array $options)
         ;
     }
 
-    public function getBlockPrefix()
+    public function getBlockPrefix(): string
     {
         return 'app_book';
     }
diff --git a/tests/Application/src/Form/Type/ScienceBookType.php b/tests/Application/src/Form/Type/ScienceBookType.php
index 1a1c5da0b..da0f69ffa 100644
--- a/tests/Application/src/Form/Type/ScienceBookType.php
+++ b/tests/Application/src/Form/Type/ScienceBookType.php
@@ -19,7 +19,7 @@
 
 final class ScienceBookType extends AbstractResourceType
 {
-    public function buildForm(FormBuilderInterface $builder, array $options)
+    public function buildForm(FormBuilderInterface $builder, array $options): void
     {
         $builder
             ->add('title', TextType::class)