diff --git a/modules/behavioural_qc/php/models/behaviouraldto.class.inc b/modules/behavioural_qc/php/models/behaviouraldto.class.inc
index 891aaa1f69e..da33721c0af 100644
--- a/modules/behavioural_qc/php/models/behaviouraldto.class.inc
+++ b/modules/behavioural_qc/php/models/behaviouraldto.class.inc
@@ -126,7 +126,7 @@ class BehaviouralDTO implements \LORIS\Data\DataInstance,
      */
     public function getCenterID(): \CenterID
     {
-        return new \CenterID($this->_site);
+        return new \CenterID(strval($this->_site));
     }
 
     /**
@@ -137,7 +137,7 @@ class BehaviouralDTO implements \LORIS\Data\DataInstance,
      */
     public function getProjectID(): \ProjectID
     {
-        return new \ProjectID($this->_project);
+        return new \ProjectID(strval($this->_project));
     }
 
     /**
diff --git a/modules/behavioural_qc/php/models/conflictsdto.class.inc b/modules/behavioural_qc/php/models/conflictsdto.class.inc
index cb108b86056..bf1887f1c31 100644
--- a/modules/behavioural_qc/php/models/conflictsdto.class.inc
+++ b/modules/behavioural_qc/php/models/conflictsdto.class.inc
@@ -112,7 +112,7 @@ class ConflictsDTO implements \LORIS\Data\DataInstance,
      */
     public function getCenterID(): \CenterID
     {
-        return new \CenterID($this->_site);
+        return new \CenterID(strval($this->_site));
     }
 
     /**
@@ -123,7 +123,7 @@ class ConflictsDTO implements \LORIS\Data\DataInstance,
      */
     public function getProjectID(): \ProjectID
     {
-        return new \ProjectID($this->_project);
+        return new \ProjectID(strval($this->_project));
     }
 
     /**
diff --git a/modules/behavioural_qc/php/models/incompletedto.class.inc b/modules/behavioural_qc/php/models/incompletedto.class.inc
index 7b837e6c5c2..dea8b8861f6 100644
--- a/modules/behavioural_qc/php/models/incompletedto.class.inc
+++ b/modules/behavioural_qc/php/models/incompletedto.class.inc
@@ -112,7 +112,7 @@ class IncompleteDTO implements \LORIS\Data\DataInstance,
      */
     public function getCenterID(): \CenterID
     {
-        return new \CenterID($this->_site);
+        return new \CenterID(strval($this->_site));
     }
 
     /**
@@ -123,7 +123,7 @@ class IncompleteDTO implements \LORIS\Data\DataInstance,
      */
     public function getProjectID(): \ProjectID
     {
-        return new \ProjectID($this->_project);
+        return new \ProjectID(strval($this->_project));
     }
 
     /**