diff --git a/Controller/ManageController.php b/Controller/ManageController.php
index a70a629..73644ac 100644
--- a/Controller/ManageController.php
+++ b/Controller/ManageController.php
@@ -74,7 +74,7 @@ public function create(Request $request): Response
     {
         $type = $request->query->get('type');
 
-        if (!\in_array($type, [SharedProjectTimesheet::TYPE_CUSTOMER, SharedProjectTimesheet::TYPE_PROJECT])) {
+        if (!\in_array($type, [SharedProjectTimesheet::TYPE_CUSTOMER, SharedProjectTimesheet::TYPE_PROJECT], true)) {
             throw new InvalidArgumentException('Invalid value for type');
         }
 
@@ -134,7 +134,7 @@ public function update(SharedProjectTimesheet $sharedProject, string $shareKey,
                 $this->flashUpdateException($e);
             }
         } elseif (!$form->isSubmitted()) {
-            if (!empty($sharedProject->getPassword())) {
+            if ($sharedProject->hasPassword()) {
                 $form->get('password')->setData(ManageService::PASSWORD_DO_NOT_CHANGE_VALUE);
             }
         }
diff --git a/Entity/SharedProjectTimesheet.php b/Entity/SharedProjectTimesheet.php
index 9bf904e..667e8f3 100644
--- a/Entity/SharedProjectTimesheet.php
+++ b/Entity/SharedProjectTimesheet.php
@@ -111,6 +111,11 @@ public function getPassword(): ?string
         return $this->password;
     }
 
+    public function hasPassword(): bool
+    {
+        return $this->password !== null && $this->password !== '';
+    }
+
     public function setPassword(?string $password): void
     {
         $this->password = $password;
@@ -123,7 +128,7 @@ public function isEntryUserVisible(): bool
 
     public function setEntryUserVisible(bool $entryUserVisible): void
     {
-        $this->entryUserVisible = (bool) $entryUserVisible;
+        $this->entryUserVisible = $entryUserVisible;
     }
 
     public function isEntryRateVisible(): bool
@@ -133,7 +138,7 @@ public function isEntryRateVisible(): bool
 
     public function setEntryRateVisible(bool $entryRateVisible): void
     {
-        $this->entryRateVisible = (bool) $entryRateVisible;
+        $this->entryRateVisible = $entryRateVisible;
     }
 
     public function hasRecordMerging(): bool
diff --git a/Form/SharedProjectFormType.php b/Form/SharedProjectFormType.php
index 3919d29..f69c461 100644
--- a/Form/SharedProjectFormType.php
+++ b/Form/SharedProjectFormType.php
@@ -118,7 +118,8 @@ public function configureOptions(OptionsResolver $resolver): void
 
     public function finishView(FormView $view, FormInterface $form, array $options): void
     {
-        if (!empty($form->get('password')->getData())) {
+        $data = $form->get('password')->getData();
+        if (is_string($data) && trim($data) !== '') {
             $view['password']->vars['value'] = ManageService::PASSWORD_DO_NOT_CHANGE_VALUE;
         }
     }
diff --git a/Model/TimeRecord.php b/Model/TimeRecord.php
index 05b18ff..3c2aed4 100644
--- a/Model/TimeRecord.php
+++ b/Model/TimeRecord.php
@@ -44,7 +44,7 @@ private function __construct(
 
     public static function fromTimesheet(Timesheet $timesheet, string $mergeMode = RecordMergeMode::MODE_MERGE): TimeRecord
     {
-        if (!\in_array($mergeMode, self::VALID_MERGE_MODES)) {
+        if (!\in_array($mergeMode, self::VALID_MERGE_MODES, true)) {
             throw new \InvalidArgumentException("Invalid merge mode given: $mergeMode");
         }
 
diff --git a/Repository/SharedProjectTimesheetRepository.php b/Repository/SharedProjectTimesheetRepository.php
index bff9059..da5f33a 100644
--- a/Repository/SharedProjectTimesheetRepository.php
+++ b/Repository/SharedProjectTimesheetRepository.php
@@ -73,7 +73,7 @@ public function getProjects(SharedProjectTimesheet $sharedProject): array
         }
 
         /** @var ProjectRepository $projectRepository */
-        $projectRepository = $this->_em->getRepository(Project::class);
+        $projectRepository = $this->_em->getRepository(Project::class); // @phpstan-ignore-line
 
         $query = new ProjectQuery();
         $query->setCustomers([$sharedProject->getCustomer()]);
diff --git a/Service/ManageService.php b/Service/ManageService.php
index 0e85641..a1a6b24 100644
--- a/Service/ManageService.php
+++ b/Service/ManageService.php
@@ -51,10 +51,10 @@ public function update(SharedProjectTimesheet $sharedProjectTimesheet, ?string $
         }
 
         // Handle password
-        $currentHashedPassword = !empty($sharedProjectTimesheet->getPassword()) ? $sharedProjectTimesheet->getPassword() : null;
+        $currentHashedPassword = $sharedProjectTimesheet->hasPassword() ? $sharedProjectTimesheet->getPassword() : null;
 
         if ($newPassword !== self::PASSWORD_DO_NOT_CHANGE_VALUE) {
-            if (!empty($newPassword)) {
+            if (is_string($newPassword) && $newPassword !== '') {
                 $encodedPassword = $this->passwordHasherFactory->getPasswordHasher('customer_portal')->hash($newPassword);
                 $sharedProjectTimesheet->setPassword($encodedPassword);
             } else {
diff --git a/Service/ViewService.php b/Service/ViewService.php
index 3ba39aa..dd830f6 100644
--- a/Service/ViewService.php
+++ b/Service/ViewService.php
@@ -50,7 +50,7 @@ public function hasAccess(SharedProjectTimesheet $sharedProject, ?string $givenP
 
             if (!$this->request->getSession()->has($sessionPasswordKey)) {
                 // Check given password
-                if (empty($givenPassword) || !$this->passwordHasherFactory->getPasswordHasher('customer_portal')->verify($hashedPassword, $givenPassword)) {
+                if ($givenPassword === null || $givenPassword === '' || !$this->passwordHasherFactory->getPasswordHasher('customer_portal')->verify($hashedPassword, $givenPassword)) {
                     return false;
                 }
 
diff --git a/phpstan.neon b/phpstan.neon
index 402a049..f91aff3 100644
--- a/phpstan.neon
+++ b/phpstan.neon
@@ -1,9 +1,10 @@
 includes:
-  - %rootDir%/../phpstan-symfony/extension.neon
-  - %rootDir%/../phpstan-symfony/rules.neon
-  - %rootDir%/../phpstan-doctrine/extension.neon
-  - %rootDir%/../phpstan-doctrine/rules.neon
-  - %rootDir%/../phpstan/conf/bleedingEdge.neon
+    - %rootDir%/../phpstan-symfony/extension.neon
+    - %rootDir%/../phpstan-symfony/rules.neon
+    - %rootDir%/../phpstan-doctrine/extension.neon
+    - %rootDir%/../phpstan-doctrine/rules.neon
+    - %rootDir%/../phpstan-strict-rules/rules.neon
+    - %rootDir%/../phpstan/conf/bleedingEdge.neon
 
 parameters:
     level: 7