diff --git a/src/opnsense/mvc/app/models/OPNsense/Interfaces/Vip.php b/src/opnsense/mvc/app/models/OPNsense/Interfaces/Vip.php
index 1aca7dc8b..25f5e8772 100644
--- a/src/opnsense/mvc/app/models/OPNsense/Interfaces/Vip.php
+++ b/src/opnsense/mvc/app/models/OPNsense/Interfaces/Vip.php
@@ -41,21 +41,33 @@ class Vip extends BaseModel
     public function performValidation($validateFullModel = false)
     {
         $messages = parent::performValidation($validateFullModel);
-        $vips = [];
+
+        $unqiue_addrs = [];
         $carp_vhids = [];
+        $vips = [];
 
         // collect changed VIP entries
         $vip_fields = ['mode', 'subnet', 'subnet_bits', 'password', 'vhid', 'interface'];
         foreach ($this->getFlatNodes() as $key => $node) {
             $tagName = $node->getInternalXMLTagName();
             $parentNode = $node->getParentNode();
+
             if ($validateFullModel || $node->isFieldChanged()) {
                 if ($parentNode->getInternalXMLTagName() === 'vip' && in_array($tagName, $vip_fields)) {
-                    $parentKey = $parentNode->__reference;
-                    $vips[$parentKey] = $parentNode;
+                    $vips[$parentNode->__reference] = $parentNode;
                 }
             }
+
+            if ($parentNode->getInternalXMLTagName() === 'vip' && $tagName == 'subnet') {
+                $addr = (string)$parentNode->subnet;
+                if (Util::isLinkLocal($addr)) {
+                    $addr .= '@' . (string)$parentNode->interface;
+                }
+                $unique_addrs[$parentNode->__reference] = $addr;
+            }
+
             $vhid_key = sprintf("%s_%s", $parentNode->interface, $parentNode->vhid);
+
             if ((string)$parentNode->mode == 'carp' && !isset($carp_vhids[$vhid_key])) {
                 $carp_vhids[$vhid_key] = $parentNode;
             }
@@ -151,6 +163,17 @@ class Vip extends BaseModel
                     )
                 );
             }
+
+            /* ensure address is unique; for link-local we test with scope attached */
+            $addr = (string)$node->subnet;
+            if (Util::isLinkLocal($addr)) {
+                $addr .= '@' . (string)$node->interface;
+            }
+            foreach ($unique_addrs as $refKey => $refAddr) {
+                if ($refKey != $key && $refAddr === $addr) {
+                    $messages->appendMessage(new Message(gettext('Address already assigned.'), $key . '.subnet'));
+                }
+            }
         }
 
         return $messages;
diff --git a/src/opnsense/mvc/app/models/OPNsense/Interfaces/Vip.xml b/src/opnsense/mvc/app/models/OPNsense/Interfaces/Vip.xml
index 0c5a7ede0..d7e1a6e25 100644
--- a/src/opnsense/mvc/app/models/OPNsense/Interfaces/Vip.xml
+++ b/src/opnsense/mvc/app/models/OPNsense/Interfaces/Vip.xml
@@ -21,12 +21,6 @@
             </mode>
             <subnet type=".\VipNetworkField">
                 <!-- required, but validated in model -->
-                <Constraints>
-                    <check001>
-                        <ValidationMessage>Address already assigned.</ValidationMessage>
-                        <type>UniqueConstraint</type>
-                    </check001>
-                </Constraints>
             </subnet>
             <subnet_bits type=".\VipNetworkField">
                 <!-- required, but validated in model -->