diff --git a/Controller/Controller.php b/Controller/Controller.php
index 3b2fb4c..b1cbc42 100644
--- a/Controller/Controller.php
+++ b/Controller/Controller.php
@@ -66,7 +66,7 @@ class Controller extends ModuleAbstract implements WebInterface
      * @var string[]
      * @since 1.0.0
      */
-    protected static $providing = [];
+    protected static array $providing = [];
 
     /**
      * Dependencies.
@@ -74,5 +74,5 @@ class Controller extends ModuleAbstract implements WebInterface
      * @var string[]
      * @since 1.0.0
      */
-    protected static $dependencies = [];
+    protected static array $dependencies = [];
 }
diff --git a/Models/DepartmentMapper.php b/Models/DepartmentMapper.php
index a8d80b5..89587b0 100644
--- a/Models/DepartmentMapper.php
+++ b/Models/DepartmentMapper.php
@@ -32,7 +32,7 @@ final class DepartmentMapper extends DataMapperAbstract
      * @var array<string, array<string, bool|string>>
      * @since 1.0.0
      */
-    protected static $columns = [
+    protected static array $columns = [
         'organization_department_id'             => ['name' => 'organization_department_id', 'type' => 'int', 'internal' => 'id'],
         'organization_department_name'           => ['name' => 'organization_department_name', 'type' => 'string', 'internal' => 'name'],
         'organization_department_description'    => ['name' => 'organization_department_description', 'type' => 'string', 'internal' => 'description'],
@@ -48,7 +48,7 @@ final class DepartmentMapper extends DataMapperAbstract
      * @var array<string, array<string, string>>
      * @since 1.0.0
      */
-    protected static $belongsTo = [
+    protected static array $belongsTo = [
         'unit'   => [
             'mapper' => UnitMapper::class,
             'dest'   => 'organization_department_unit',
@@ -65,7 +65,7 @@ final class DepartmentMapper extends DataMapperAbstract
      * @var string
      * @since 1.0.0
      */
-    protected static $table = 'organization_department';
+    protected static string $table = 'organization_department';
 
     /**
      * Primary field name.
@@ -73,5 +73,5 @@ final class DepartmentMapper extends DataMapperAbstract
      * @var string
      * @since 1.0.0
      */
-    protected static $primaryField = 'organization_department_id';
+    protected static string $primaryField = 'organization_department_id';
 }
diff --git a/Models/PositionMapper.php b/Models/PositionMapper.php
index d7a6a09..64d9ce3 100644
--- a/Models/PositionMapper.php
+++ b/Models/PositionMapper.php
@@ -33,7 +33,7 @@ final class PositionMapper extends DataMapperAbstract
      * @var array<string, array<string, bool|string>>
      * @since 1.0.0
      */
-    protected static $columns = [
+    protected static array $columns = [
         'organization_position_id'             => ['name' => 'organization_position_id', 'type' => 'int', 'internal' => 'id'],
         'organization_position_name'           => ['name' => 'organization_position_name', 'type' => 'string', 'internal' => 'name'],
         'organization_position_description'    => ['name' => 'organization_position_description', 'type' => 'string', 'internal' => 'description'],
@@ -49,7 +49,7 @@ final class PositionMapper extends DataMapperAbstract
      * @var array<string, array<string, string>>
      * @since 1.0.0
      */
-    protected static $belongsTo = [
+    protected static array $belongsTo = [
         'parent'     => [
             'mapper' => self::class,
             'dest'   => 'organization_position_parent',
@@ -66,7 +66,7 @@ final class PositionMapper extends DataMapperAbstract
      * @var string
      * @since 1.0.0
      */
-    protected static $table = 'organization_position';
+    protected static string $table = 'organization_position';
 
     /**
      * Primary field name.
@@ -74,5 +74,5 @@ final class PositionMapper extends DataMapperAbstract
      * @var string
      * @since 1.0.0
      */
-    protected static $primaryField = 'organization_position_id';
+    protected static string $primaryField = 'organization_position_id';
 }
diff --git a/Models/UnitMapper.php b/Models/UnitMapper.php
index 79a0550..be127f2 100644
--- a/Models/UnitMapper.php
+++ b/Models/UnitMapper.php
@@ -32,7 +32,7 @@ final class UnitMapper extends DataMapperAbstract
      * @var array<string, array<string, bool|string>>
      * @since 1.0.0
      */
-    protected static $columns = [
+    protected static array $columns = [
         'organization_unit_id'             => ['name' => 'organization_unit_id', 'type' => 'int', 'internal' => 'id'],
         'organization_unit_name'           => ['name' => 'organization_unit_name', 'type' => 'string', 'internal' => 'name'],
         'organization_unit_description'    => ['name' => 'organization_unit_description', 'type' => 'string', 'internal' => 'description'],
@@ -47,7 +47,7 @@ final class UnitMapper extends DataMapperAbstract
      * @var array<string, array<string, string>>
      * @since 1.0.0
      */
-    protected static $belongsTo = [
+    protected static array $belongsTo = [
         'unit' => [
             'mapper' => self::class,
             'dest'   => 'organization_uni_parent',
@@ -64,7 +64,7 @@ final class UnitMapper extends DataMapperAbstract
      * @var string
      * @since 1.0.0
      */
-    protected static $table = 'organization_unit';
+    protected static string $table = 'organization_unit';
 
     /**
      * Primary field name.
@@ -72,5 +72,5 @@ final class UnitMapper extends DataMapperAbstract
      * @var string
      * @since 1.0.0
      */
-    protected static $primaryField = 'organization_unit_id';
+    protected static string $primaryField = 'organization_unit_id';
 }