diff --git a/src/etc/inc/upgrade_config.inc b/src/etc/inc/upgrade_config.inc
index 861f28aa6e..4317ecbe0b 100644
--- a/src/etc/inc/upgrade_config.inc
+++ b/src/etc/inc/upgrade_config.inc
@@ -6401,6 +6401,26 @@ function upgrade_215_to_216() {
                return;
        }
 
+       /* Deprecated method. */
+       function upgrade216_ipsec_create_vtimap($ikeid, $idx) {
+               $assigned = array_column($config['ipsec']['vtimaps']['item'], 'ifnum');
+               asort($assigned, SORT_NUMERIC);
+               $new = 1;
+               foreach ($assigned as $ipsecifnum) {
+                       if ($ipsecifnum != $new) {
+                               break;
+                       }
+                       if ($new++ > 32767) {
+                               return(NULL);
+                       }
+               }
+               return array(
+                       "reqid" => $ikeid,
+                       "index" => $idx,
+                       "ifnum" => $new
+               );
+       }
+
        $iflist = get_configured_interface_list_by_realif(true);
 
        foreach ($config['ipsec']['vtimaps']['item'] as $idx => $vtimap) {
@@ -6408,7 +6428,7 @@ function upgrade_215_to_216() {
                        continue;
                }
 
-               $new_vtimap = ipsec_create_vtimap($vtimap['reqid'],
+               $new_vtimap = upgrade216_ipsec_create_vtimap($vtimap['reqid'],
                    $vtimap['index']);
 
                /*