diff --git a/admin/tool/lp/classes/external/competency_summary_exporter.php b/admin/tool/lp/classes/external/competency_summary_exporter.php
index 163e103e076..af85059422f 100644
--- a/admin/tool/lp/classes/external/competency_summary_exporter.php
+++ b/admin/tool/lp/classes/external/competency_summary_exporter.php
@@ -125,7 +125,7 @@ class competency_summary_exporter extends \core\external\exporter {
         $result->scaleconfiguration = $scaleconfiguration;
         $result->scaleid = $scaleid;
 
-        $level = $competency->get('level');
+        $level = $competency->get_level();
         $taxonomy = $this->related['framework']->get_taxonomy($level);
         $result->taxonomyterm = (string) (competency_framework::get_taxonomies_list()[$taxonomy]);
 
diff --git a/competency/classes/external/evidence_exporter.php b/competency/classes/external/evidence_exporter.php
index 44fcbb2ec43..5ad314da4ed 100644
--- a/competency/classes/external/evidence_exporter.php
+++ b/competency/classes/external/evidence_exporter.php
@@ -78,7 +78,7 @@ class evidence_exporter extends \core\external\persistent_exporter {
             $other['actionuser'] = $actionuser;
         }
 
-        $other['description'] = $this->persistent->get('description');
+        $other['description'] = $this->persistent->get_description();
 
         $other['userdate'] = userdate($this->persistent->get('timecreated'));
 
diff --git a/lib/classes/persistent.php b/lib/classes/persistent.php
index 40a7d1fa8c6..d45b929d9cb 100644
--- a/lib/classes/persistent.php
+++ b/lib/classes/persistent.php
@@ -112,6 +112,9 @@ abstract class persistent {
      * @return $this
      */
     final public function set($property, $value) {
+        if (!static::has_property($property)) {
+            throw new coding_exception('Unexpected property \'' . s($property) .'\' requested.');
+        }
         $methodname = 'set_' . $property;
         if (method_exists($this, $methodname)) {
             $this->$methodname($value);
@@ -133,6 +136,9 @@ abstract class persistent {
      * @return mixed
      */
     final public function get($property) {
+        if (!static::has_property($property)) {
+            throw new coding_exception('Unexpected property \'' . s($property) .'\' requested.');
+        }
         $methodname = 'get_' . $property;
         if (method_exists($this, $methodname)) {
             return $this->$methodname();