diff --git a/badges/criteria/award_criteria.php b/badges/criteria/award_criteria.php
index 4287cddc646..8cc0a088952 100644
--- a/badges/criteria/award_criteria.php
+++ b/badges/criteria/award_criteria.php
@@ -223,7 +223,7 @@ abstract class award_criteria {
         if (!empty($this->params)) {
             if (count($this->params) > 1) {
                 echo $OUTPUT->box(get_string('criteria_descr_' . $this->criteriatype, 'badges',
-                        strtoupper($agg[$data->get_aggregation_method($this->criteriatype)])), array('clearfix'));
+                        core_text::strtoupper($agg[$data->get_aggregation_method($this->criteriatype)])), array('clearfix'));
             } else {
                 echo $OUTPUT->box(get_string('criteria_descr_single_' . $this->criteriatype , 'badges'), array('clearfix'));
             }
diff --git a/badges/criteria/award_criteria_overall.php b/badges/criteria/award_criteria_overall.php
index 32e871117b4..91a6a9da05e 100644
--- a/badges/criteria/award_criteria_overall.php
+++ b/badges/criteria/award_criteria_overall.php
@@ -60,7 +60,7 @@ class award_criteria_overall extends award_criteria {
                 echo html_writer::table($table);
             } else {
                 echo $OUTPUT->box(get_string('criteria_descr_' . $this->criteriatype, 'badges',
-                        strtoupper($agg[$data->get_aggregation_method()])), 'clearfix');
+                        core_text::strtoupper($agg[$data->get_aggregation_method()])), 'clearfix');
             }
             echo $OUTPUT->box_end();
         }
diff --git a/badges/renderer.php b/badges/renderer.php
index 52f7205f257..99c099ef8d8 100644
--- a/badges/renderer.php
+++ b/badges/renderer.php
@@ -362,7 +362,7 @@ class core_badges_renderer extends plugin_renderer_base {
                     $items[] = get_string('criteria_descr_single_' . $type , 'badges') . $c->get_details();
                 } else {
                     $items[] = get_string('criteria_descr_' . $type , 'badges',
-                            strtoupper($agg[$badge->get_aggregation_method($type)])) . $c->get_details();
+                            core_text::strtoupper($agg[$badge->get_aggregation_method($type)])) . $c->get_details();
                 }
             }
         }
@@ -716,7 +716,7 @@ class core_badges_renderer extends plugin_renderer_base {
             }
         } else {
             $output .= get_string('criteria_descr_' . $short . BADGE_CRITERIA_TYPE_OVERALL, 'badges',
-                                    strtoupper($agg[$badge->get_aggregation_method()]));
+                                    core_text::strtoupper($agg[$badge->get_aggregation_method()]));
         }
         $items = array();
         unset($badge->criteria[BADGE_CRITERIA_TYPE_OVERALL]);
@@ -725,7 +725,7 @@ class core_badges_renderer extends plugin_renderer_base {
                 $items[] = get_string('criteria_descr_single_' . $short . $type , 'badges') . $c->get_details($short);
             } else {
                 $items[] = get_string('criteria_descr_' . $short . $type , 'badges',
-                        strtoupper($agg[$badge->get_aggregation_method($type)])) . $c->get_details($short);
+                        core_text::strtoupper($agg[$badge->get_aggregation_method($type)])) . $c->get_details($short);
             }
         }
         $output .= html_writer::alist($items, array(), 'ul');