diff --git a/lib/Carriers.lib.php b/lib/Carriers.lib.php
index f91fc6d..2b19aff 100644
--- a/lib/Carriers.lib.php
+++ b/lib/Carriers.lib.php
@@ -3,6 +3,10 @@
 class Carriers {
 
     const CARRIER_REGEXES = [
+        [
+            "carrier" => "usps_gsbarcode", // USPS barcodes with GS character
+            "pattern" => "/^\\x1D?420[0-9]{5,11}\\x1D?[0-9]{10,}\\x1D?$/"
+        ],
         [
             "carrier" => "ups_mi_datamatrix",
             "pattern" => "/^([^\\t]*\\t[^\\t]*){13}$/"
@@ -47,14 +51,6 @@ class Carriers {
             "carrier" => "usps",
             "pattern" => "/^420[0-9]{5}[0-9]+$/"
         ],
-        [
-            "carrier" => "usps",
-            "pattern" => "/^\\x1D?420[0-9]{5,11}\\x1D?[0-9]{10,}\\x1D?$/"
-        ],
-        [
-            "carrier" => "usps",
-            "pattern" => "/^420[0-9]{5,11}\\x1D[0-9]{10,}\\x1D?$/"
-        ],
         [
             "carrier" => "fedex",
             "pattern" => "/^[0-9]{15}$/"
diff --git a/lib/Tracking.lib.php b/lib/Tracking.lib.php
index 4e74ddd..1caa165 100644
--- a/lib/Tracking.lib.php
+++ b/lib/Tracking.lib.php
@@ -19,6 +19,8 @@ class Tracking {
         }
 
         switch ($carriercode) {
+            case "usps_gsbarcode":
+                return Tracking_USPS_gsbarcode::track($code);
             case "ups_mi_datamatrix":
                 return Tracking_UPS_MailInnovations_DataMatrix::track($code);
             case "fedex_pdf417":
diff --git a/lib/TrackingBarcode.lib.php b/lib/TrackingBarcode.lib.php
index c9050f7..044f48b 100644
--- a/lib/TrackingBarcode.lib.php
+++ b/lib/TrackingBarcode.lib.php
@@ -30,7 +30,7 @@ class TrackingBarcode {
     public function getCarrier(): string {
         $carrier = "";
         foreach (Carriers::CARRIER_REGEXES as $p) {
-            if (preg_match($p["pattern"]."i", $this->code)) {
+            if (preg_match($p["pattern"], strtoupper($this->code))) {
                 $carrier = $p["carrier"];
                 break;
             }
diff --git a/lib/Tracking_USPS_gsbarcode.lib.php b/lib/Tracking_USPS_gsbarcode.lib.php
new file mode 100644
index 0000000..eebcd5c
--- /dev/null
+++ b/lib/Tracking_USPS_gsbarcode.lib.php
@@ -0,0 +1,23 @@
+<?php
+
+class Tracking_USPS_gsbarcode {
+
+    /**
+     *
+     * @global type $SETTINGS
+     * @param string $code
+     * @return \TrackingInfo
+     * @throws TrackingException
+     */
+    public static function track(string $code): TrackingInfo {
+        if (strpos($code, "\x1D") === 0) {
+            $code = substr($code, 1);
+        }
+        $codeparts = explode("\x1D", $code);
+
+        $realcode = $codeparts[1];
+
+        return Tracking::track($realcode, "usps");
+    }
+
+}