diff --git a/system/controllers/customers.php b/system/controllers/customers.php
index baee9405..511040e3 100644
--- a/system/controllers/customers.php
+++ b/system/controllers/customers.php
@@ -541,11 +541,13 @@ switch ($action) {
             $userDiff = true;
         }
         if ($oldPppoeUsername != $pppoe_username) {
-            if(ORM::for_table('tbl_customers')->where('pppoe_username', $pppoe_username)->find_one()){
-                $msg.= Lang::T('PPPoE Username already used by another customer') . '<br>';
-            }
-            if(ORM::for_table('tbl_customers')->where('username', $pppoe_username)->find_one()){
-                $msg.= Lang::T('PPPoE Username already used by another customer') . '<br>';
+            if(!empty($pppoe_username)){
+                if(ORM::for_table('tbl_customers')->where('pppoe_username', $pppoe_username)->find_one()){
+                    $msg.= Lang::T('PPPoE Username already used by another customer') . '<br>';
+                }
+                if(ORM::for_table('tbl_customers')->where('username', $pppoe_username)->find_one()){
+                    $msg.= Lang::T('PPPoE Username already used by another customer') . '<br>';
+                }
             }
             $pppoeDiff = true;
         }
diff --git a/system/lan/english.json b/system/lan/english.json
index e775eb4f..5797a2d0 100644
--- a/system/lan/english.json
+++ b/system/lan/english.json
@@ -694,5 +694,6 @@
     "_": "-",
     "Routers_Maps": "Routers Maps",
     "Routers_Geo_Location_Information": "Routers Geo Location Information",
-    "Coverage": "Coverage"
+    "Coverage": "Coverage",
+    "PPPoE_Username_already_used_by_another_customer": "PPPoE Username already used by another customer"
 }
\ No newline at end of file