diff --git a/php/savesettings.php b/php/savesettings.php
index 5a67f449..22bbc943 100644
--- a/php/savesettings.php
+++ b/php/savesettings.php
@@ -74,7 +74,7 @@ function validDomain($domain_name)
 				}
 
 				// Validate secondary IP
-				if (!validIP($secondaryIP))
+				if (!validIP($secondaryIP) && strlen($secondaryIP) > 0)
 				{
 					$error .= "Secondary IP (".$secondaryIP.") is invalid!<br>";
 				}