diff --git a/Parser.php b/Parser.php
index 2d2cbd1..367e111 100644
--- a/Parser.php
+++ b/Parser.php
@@ -358,7 +358,7 @@ private function parse()
     private function ip2bin($ip)
     {
         if (filter_var($ip, FILTER_VALIDATE_IP, FILTER_FLAG_IPV4) !== false) {
-            return base_convert(ip2long($ip), 10, 2);
+            return base_convert(sprintf('%u', ip2long($ip)), 10, 2);
         }
         
         if (filter_var($ip, FILTER_VALIDATE_IP, FILTER_FLAG_IPV6) === false) {