diff --git a/api/src/Repositories/AbstractWorkingHoursViewRepository.php b/api/src/Repositories/AbstractWorkingHoursViewRepository.php
index 7ad6843..dfbbb91 100644
--- a/api/src/Repositories/AbstractWorkingHoursViewRepository.php
+++ b/api/src/Repositories/AbstractWorkingHoursViewRepository.php
@@ -17,8 +17,8 @@ use TorstenHettstedt\TimekeepingApi\Models\WorkingHoursView;
 abstract class AbstractWorkingHoursViewRepository implements RepositoryReaderInterface
 {
 
-    protected const SQL_SELECT = '';
-    protected const SQL_WHERE  = '';
+    protected const string SQL_SELECT = '';
+    protected const string SQL_WHERE  = '';
 
     protected PeriodDesignationEnum $periodDesignation;
 
diff --git a/api/src/Repositories/WorkingHoursMonthlyViewRepository.php b/api/src/Repositories/WorkingHoursMonthlyViewRepository.php
index 6a478ed..7989e84 100644
--- a/api/src/Repositories/WorkingHoursMonthlyViewRepository.php
+++ b/api/src/Repositories/WorkingHoursMonthlyViewRepository.php
@@ -12,7 +12,7 @@ use TorstenHettstedt\TimekeepingApi\Models\PeriodDesignationEnum;
 class WorkingHoursMonthlyViewRepository extends AbstractWorkingHoursViewRepository
 {
 
-    protected const SQL_SELECT = <<<SQL
+    protected const string SQL_SELECT = <<<SQL
         select
             "Monat" as "period",
             "Gesamtarbeitszeit" as "totalHours",