diff --git a/lib/dml/oci_native_moodle_database.php b/lib/dml/oci_native_moodle_database.php
index f9284ccd9a6..8c0538ce301 100644
--- a/lib/dml/oci_native_moodle_database.php
+++ b/lib/dml/oci_native_moodle_database.php
@@ -1118,11 +1118,13 @@ class oci_native_moodle_database extends moodle_database {
     }
 
     public function sql_bitor($int1, $int2) {
+        // TODO: this can not work because the number of params does not match
         return '((' . $int1 . ') + (' . $int2 . ') - ' . $this->sql_bitand($int1, $int2) . ')';
     }
 
     public function sql_bitxor($int1, $int2) {
-        return '((' . $int1 . ') # (' . $int2 . '))';
+        // TODO: this can not work because the number of params does not match
+        return '(' . sql_bitor($int1, $int2) . ' - ' . $this->sql_bitand($int1, $int2) . ')';
     }
 
     /**