diff --git a/src/opnsense/mvc/app/models/OPNsense/Base/FieldTypes/CertificateField.php b/src/opnsense/mvc/app/models/OPNsense/Base/FieldTypes/CertificateField.php
index 347d04bca..53a74f8b8 100644
--- a/src/opnsense/mvc/app/models/OPNsense/Base/FieldTypes/CertificateField.php
+++ b/src/opnsense/mvc/app/models/OPNsense/Base/FieldTypes/CertificateField.php
@@ -29,7 +29,7 @@
  */
 namespace OPNsense\Base\FieldTypes;
 
-use Phalcon\Validation\Validator\InclusionIn;
+use OPNsense\Base\Validators\CsvListValidator;
 use OPNsense\Core\Config;
 
 /**
@@ -49,6 +49,11 @@ class CertificateField extends BaseField
      */
     private $certificateType = "cert";
 
+    /**
+     * @var bool field may contain multiple certs at once
+     */
+    private $internalMultiSelect = false;
+
     /**
      * @var string default validation message string
      */
@@ -59,7 +64,6 @@ class CertificateField extends BaseField
      */
     private static $internalOptionList = array();
 
-
     /**
      * set certificate type (cert/ca)
      * @param $value certificate type
@@ -73,6 +77,19 @@ class CertificateField extends BaseField
         }
     }
 
+    /**
+     * select if multiple certs may be selected at once
+     * @param $value boolean value Y/N
+     */
+    public function setMultiple($value)
+    {
+        if (trim(strtoupper($value)) == "Y") {
+            $this->internalMultiSelect = true;
+        } else {
+            $this->internalMultiSelect = false;
+        }
+    }
+
     /**
      * generate validation data (list of certificates)
      */
@@ -97,8 +114,10 @@ class CertificateField extends BaseField
         if (!$this->internalIsRequired) {
             $result[""] = array("value" => gettext("none"), "selected" => 0);
         }
+
+        $certs = explode(',', $this->internalValue);
         foreach (self::$internalOptionList as $optKey => $optValue) {
-            if ($optKey == $this->internalValue) {
+            if (in_array($optKey, $certs)) {
                 $selected = 1;
             } else {
                 $selected = 0;
@@ -117,7 +136,7 @@ class CertificateField extends BaseField
     {
         $validators = parent::getValidators();
         if ($this->internalValue != null) {
-            $validators[] = new InclusionIn(array('message' => $this->internalValidationMessage,
+            $validators[] = new CsvListValidator(array('message' => $this->internalValidationMessage,
                 'domain'=>array_keys(self::$internalOptionList)));
         }
         return $validators;