diff --git a/smppclient.class.php b/smppclient.class.php
index 7732471..b484dad 100644
--- a/smppclient.class.php
+++ b/smppclient.class.php
@@ -320,7 +320,7 @@ public function sendSMS(SmppAddress $from, SmppAddress $to, $message, $tags=null
 				$seqnum = 1;
 				foreach ($parts as $part) {
 					$udh = pack('cccccc',5,0,3,substr($csmsReference,1,1),count($parts),$seqnum);
-					$res = $this->submit_sm($from, $to, $udh.$part, $tags, $dataCoding, $priority, $scheduleDeliveryTime, $validityPeriod, (SmppClient::$sms_esm_class|0x40));
+					$res = $this->submit_sm($from, $to, $udh.$part, $tags, $dataCoding, $priority, $scheduleDeliveryTime, $validityPeriod, (SmppClient::$sms_esm_class|SMPP::ESM_UDHI));
 					$seqnum++;
 				}
 				return $res;
@@ -908,7 +908,7 @@ class SMPP
 	const ESM_DELIVER_CONV_ABORT = 0x18;
 	const ESM_DELIVER_IDN = 0x20; // Intermediate delivery notification
 	// ESM bits 7-6 
-	const ESM_UHDI = 0x40;
+	const ESM_UDHI = 0x40;
 	const ESM_REPLYPATH = 0x80;
 	
 	// SMPP v3.4 - 5.2.17 page 124