diff --git a/src/Asset/AssetCollector.php b/src/Asset/AssetCollector.php
index 6624347..5a4692b 100644
--- a/src/Asset/AssetCollector.php
+++ b/src/Asset/AssetCollector.php
@@ -86,7 +86,7 @@ class AssetCollector implements AssetCollectorInterface {
    * @param array $libraries
    *   A list of CSS libraries.
    */
-  protected function buildCssForEntity(EntityInterface $entity, array $theme_info, &$libraries) {
+  protected function buildCssForEntity(EntityInterface $entity, array $theme_info, array &$libraries) {
     foreach ($theme_info as $key => $value) {
       // If the entity type doesn't match just skip.
       if ($key !== $entity->getEntityTypeId()) {
diff --git a/src/Asset/AssetRendererInterface.php b/src/Asset/AssetRendererInterface.php
index 0202036..fe4b5c9 100644
--- a/src/Asset/AssetRendererInterface.php
+++ b/src/Asset/AssetRendererInterface.php
@@ -20,6 +20,6 @@ interface AssetRendererInterface {
    * @return array
    *   The renderable array for the assets.
    */
-  public function render($entities, $use_default_css = TRUE, $optimize_css = TRUE);
+  public function render(array $entities, $use_default_css = TRUE, $optimize_css = TRUE);
 
 }
diff --git a/src/Event/PrintCssAlterEvent.php b/src/Event/PrintCssAlterEvent.php
index c8cc584..9d638b8 100644
--- a/src/Event/PrintCssAlterEvent.php
+++ b/src/Event/PrintCssAlterEvent.php
@@ -31,7 +31,7 @@ class PrintCssAlterEvent extends Event {
    * @param array $entities
    *   An array of entities we're rendering.
    */
-  public function __construct(array &$build, $entities) {
+  public function __construct(array &$build, array $entities) {
     $this->build = &$build;
     $this->entities = $entities;
   }
diff --git a/src/Event/PrintHtmlAlterEvent.php b/src/Event/PrintHtmlAlterEvent.php
index 131c93b..3d4b1e0 100644
--- a/src/Event/PrintHtmlAlterEvent.php
+++ b/src/Event/PrintHtmlAlterEvent.php
@@ -31,7 +31,7 @@ class PrintHtmlAlterEvent extends Event {
    * @param array $entities
    *   An array of entities we're rendering.
    */
-  public function __construct(&$html, $entities) {
+  public function __construct(&$html, array $entities) {
     $this->html = &$html;
     $this->entities = $entities;
   }
diff --git a/src/Plugin/Block/PrintLinks.php b/src/Plugin/Block/PrintLinks.php
index 8ad7e61..0848892 100644
--- a/src/Plugin/Block/PrintLinks.php
+++ b/src/Plugin/Block/PrintLinks.php
@@ -42,7 +42,7 @@ class PrintLinks extends BlockBase implements ContainerFactoryPluginInterface {
    * @param \Drupal\entity_print\Plugin\ExportTypeManagerInterface $exportTypeManager
    *   The export type manager.
    */
-  public function __construct(array $configuration, $plugin_id, $plugin_definition, ExportTypeManagerInterface $exportTypeManager) {
+  public function __construct(array $configuration, $plugin_id, array $plugin_definition, ExportTypeManagerInterface $exportTypeManager) {
     $this->exportTypeManager = $exportTypeManager;
     parent::__construct($configuration, $plugin_id, $plugin_definition);
   }
diff --git a/src/PrintEngineException.php b/src/PrintEngineException.php
index 065738f..4226e73 100644
--- a/src/PrintEngineException.php
+++ b/src/PrintEngineException.php
@@ -83,7 +83,7 @@ class PrintEngineException extends \Exception {
    * @return bool
    *   TRUE if anyone of the patterns match otherwise FALSE.
    */
-  protected function evalulateRegex($patterns, $subject) {
+  protected function evalulateRegex(array $patterns, $subject) {
     foreach ($patterns as $pattern) {
       if (preg_match($pattern, $subject, $matches)) {
         return TRUE;
diff --git a/tests/src/Kernel/PrintLinkTest.php b/tests/src/Kernel/PrintLinkTest.php
index 12dd247..7dd5f64 100644
--- a/tests/src/Kernel/PrintLinkTest.php
+++ b/tests/src/Kernel/PrintLinkTest.php
@@ -58,7 +58,7 @@ class PrintLinkTest extends KernelTestBase {
    * @return \Drupal\entity_print\Plugin\Block\PrintLinks
    *   The loaded block.
    */
-  protected function getBlock($config = []) {
+  protected function getBlock(array $config = []) {
     $manager = $this->container->get('plugin.manager.block');
     $entity = $this->getMock('Drupal\Core\Entity\EntityInterface');
     $context = new Context(ContextDefinition::create(), $entity);
diff --git a/tests/themes/entity_print_test_theme/css/entityprint-all.css b/tests/themes/entity_print_test_theme/css/entityprint-all.css
index e69de29..d461309 100644
--- a/tests/themes/entity_print_test_theme/css/entityprint-all.css
+++ b/tests/themes/entity_print_test_theme/css/entityprint-all.css
@@ -0,0 +1,3 @@
+body {
+  background: #fff;
+}
diff --git a/tests/themes/entity_print_test_theme/css/entityprint-module.css b/tests/themes/entity_print_test_theme/css/entityprint-module.css
index e69de29..d461309 100644
--- a/tests/themes/entity_print_test_theme/css/entityprint-module.css
+++ b/tests/themes/entity_print_test_theme/css/entityprint-module.css
@@ -0,0 +1,3 @@
+body {
+  background: #fff;
+}
diff --git a/tests/themes/entity_print_test_theme/css/entityprint-node.css b/tests/themes/entity_print_test_theme/css/entityprint-node.css
index e69de29..d461309 100644
--- a/tests/themes/entity_print_test_theme/css/entityprint-node.css
+++ b/tests/themes/entity_print_test_theme/css/entityprint-node.css
@@ -0,0 +1,3 @@
+body {
+  background: #fff;
+}
diff --git a/tests/themes/entity_print_test_theme/css/entityprint-page.css b/tests/themes/entity_print_test_theme/css/entityprint-page.css
index e69de29..d461309 100644
--- a/tests/themes/entity_print_test_theme/css/entityprint-page.css
+++ b/tests/themes/entity_print_test_theme/css/entityprint-page.css
@@ -0,0 +1,3 @@
+body {
+  background: #fff;
+}