diff --git a/lib/dml/moodle_database.php b/lib/dml/moodle_database.php
index a6dcbdc9a92..98941f37edc 100644
--- a/lib/dml/moodle_database.php
+++ b/lib/dml/moodle_database.php
@@ -2321,10 +2321,10 @@ abstract class moodle_database {
      * This function accepts variable number of string parameters.
      * All strings/fieldnames will used in the SQL concatenate statement generated.
      *
+     * @param string $arr,... expressions to be concatenated.
      * @return string The SQL to concatenate strings passed in.
-     * @uses func_get_args()  and thus parameters are unlimited OPTIONAL number of additional field names.
      */
-    public abstract function sql_concat();
+    public abstract function sql_concat(...$arr);
 
     /**
      * Returns the proper SQL to do CONCAT between the elements passed
diff --git a/lib/dml/mysqli_native_moodle_database.php b/lib/dml/mysqli_native_moodle_database.php
index c99e98fd0a4..1fca4f71b2a 100644
--- a/lib/dml/mysqli_native_moodle_database.php
+++ b/lib/dml/mysqli_native_moodle_database.php
@@ -1927,12 +1927,11 @@ class mysqli_native_moodle_database extends moodle_database {
      * Returns the proper SQL to do CONCAT between the elements passed
      * Can take many parameters
      *
-     * @param string $str,... 1 or more fields/strings to concat
+     * @param string $arr,... 1 or more fields/strings to concat
      *
      * @return string The concat sql
      */
-    public function sql_concat() {
-        $arr = func_get_args();
+    public function sql_concat(...$arr) {
         $s = implode(', ', $arr);
         if ($s === '') {
             return "''";
diff --git a/lib/dml/oci_native_moodle_database.php b/lib/dml/oci_native_moodle_database.php
index b8d55f3d1e0..5559fc64d31 100644
--- a/lib/dml/oci_native_moodle_database.php
+++ b/lib/dml/oci_native_moodle_database.php
@@ -1577,8 +1577,7 @@ class oci_native_moodle_database extends moodle_database {
         }
     }
 
-    public function sql_concat() {
-        $arr = func_get_args();
+    public function sql_concat(...$arr) {
         if (empty($arr)) {
             return " ' ' ";
         }
diff --git a/lib/dml/pdo_moodle_database.php b/lib/dml/pdo_moodle_database.php
index 4dd37dd400b..8dd9a75abd2 100644
--- a/lib/dml/pdo_moodle_database.php
+++ b/lib/dml/pdo_moodle_database.php
@@ -534,7 +534,7 @@ abstract class pdo_moodle_database extends moodle_database {
         return $this->execute($sql, $params);
     }
 
-    public function sql_concat() {
+    public function sql_concat(...$arr) {
         throw new \moodle_exception('TODO');
     }
 
diff --git a/lib/dml/pgsql_native_moodle_database.php b/lib/dml/pgsql_native_moodle_database.php
index 859917e34c6..97456d2ba6d 100644
--- a/lib/dml/pgsql_native_moodle_database.php
+++ b/lib/dml/pgsql_native_moodle_database.php
@@ -1508,8 +1508,7 @@ class pgsql_native_moodle_database extends moodle_database {
         return " $fieldname::real ";
     }
 
-    public function sql_concat() {
-        $arr = func_get_args();
+    public function sql_concat(...$arr) {
         $s = implode(' || ', $arr);
         if ($s === '') {
             return " '' ";
diff --git a/lib/dml/sqlite3_pdo_moodle_database.php b/lib/dml/sqlite3_pdo_moodle_database.php
index 2a540b85a90..c6976995611 100644
--- a/lib/dml/sqlite3_pdo_moodle_database.php
+++ b/lib/dml/sqlite3_pdo_moodle_database.php
@@ -341,11 +341,10 @@ class sqlite3_pdo_moodle_database extends pdo_moodle_database {
      * Returns the proper SQL to do CONCAT between the elements passed
      * Can take many parameters
      *
-     * @param string $element
+     * @param string $elements,...
      * @return string
      */
-    public function sql_concat() {
-        $elements = func_get_args();
+    public function sql_concat(...$elements) {
         return implode('||', $elements);
     }
 
diff --git a/lib/dml/sqlsrv_native_moodle_database.php b/lib/dml/sqlsrv_native_moodle_database.php
index 9afc56b9e8c..d7c899fd209 100644
--- a/lib/dml/sqlsrv_native_moodle_database.php
+++ b/lib/dml/sqlsrv_native_moodle_database.php
@@ -1447,9 +1447,7 @@ class sqlsrv_native_moodle_database extends moodle_database {
         return $text;
     }
 
-    public function sql_concat() {
-        $arr = func_get_args();
-
+    public function sql_concat(...$arr) {
         foreach ($arr as $key => $ele) {
             $arr[$key] = $this->sql_cast_to_char($ele);
         }
diff --git a/lib/dml/tests/dml_test.php b/lib/dml/tests/dml_test.php
index 6b18cf53114..46fa06f032c 100644
--- a/lib/dml/tests/dml_test.php
+++ b/lib/dml/tests/dml_test.php
@@ -6443,7 +6443,7 @@ class moodle_database_for_testing extends moodle_database {
     public function update_record($table, $dataobject, $bulk=false) {}
     public function set_field_select($table, $newfield, $newvalue, $select, array $params=null) {}
     public function delete_records_select($table, $select, array $params=null) {}
-    public function sql_concat() {}
+    public function sql_concat(...$arr) {}
     public function sql_concat_join($separator="' '", $elements=array()) {}
     public function sql_group_concat(string $field, string $separator = ', ', string $sort = ''): string {
         return '';
diff --git a/lib/dml/tests/fixtures/test_moodle_database.php b/lib/dml/tests/fixtures/test_moodle_database.php
index 589aafbe865..0b680e77b87 100644
--- a/lib/dml/tests/fixtures/test_moodle_database.php
+++ b/lib/dml/tests/fixtures/test_moodle_database.php
@@ -326,10 +326,10 @@ abstract class test_moodle_database extends \moodle_database {
 
     /**
      * Default implementation, throws Exception
-     * @return string $sql
+     * @return string $arr,...
      * @throws Exception
      */
-    public function sql_concat() {
+    public function sql_concat(...$arr) {
         throw new Exception("sql_concat() not implemented");
     }