diff --git a/smppclient.class.php b/smppclient.class.php
index 7732471..1b23dcd 100644
--- a/smppclient.class.php
+++ b/smppclient.class.php
@@ -518,7 +518,11 @@ protected function parseSMS(SmppPdu $pdu)
 		$dataCoding = next($ar);
 		next($ar); // sm_default_msg_id 
 		$sm_length = next($ar);
-		$message = $this->getString($ar,$sm_length);
+        if ($sm_length > 0) {                               // getString is doing "next()" on $ar
+            $message = $this->getString($ar, $sm_length);   // but it shouldn't for 0-length,not-null-terminated value
+        } else {
+            $message = null;
+        }
 		
 		// Check for optional params, and parse them
 		if (current($ar) !== false) {
@@ -1062,18 +1066,37 @@ class SmppDeliveryReceipt extends SmppSms
 	 */
 	public function parseDeliveryReceipt()
 	{
-		$numMatches = preg_match('/^id:([^ ]+) sub:(\d{1,3}) dlvrd:(\d{3}) submit date:(\d{10,12}) done date:(\d{10,12}) stat:([A-Z ]{7}) err:(\d{2,3}) text:(.*)$/si', $this->message, $matches);
+		$id = "id:(?<id>[^ ]+) ";
+		$sub = "sub:(?<sub>\d{1,3}) ";
+		$dlvrd = "dlvrd:(?<dlvrd>\d{3}) ";
+		$submitDate = "submit date:(?<submitDate>\d{10,12}) ";
+		$doneDate = "done date:(?<doneDate>\d{10,12}) ";
+		$stat = "stat:(?<stat>[A-Z ]{7}) ";
+		$err = "(err:(?<err>\d{2,3}) )?";
+		$text = "text:(?<text>.*)";
+		$numMatches = preg_match("/^{$id}{$sub}{$dlvrd}{$submitDate}{$doneDate}{$stat}{$err}{$text}$/si", $this->message, $matches);
 		if ($numMatches == 0) {
-			throw new InvalidArgumentException('Could not parse delivery receipt: '.$this->message."\n".bin2hex($this->body));	
+			throw new InvalidArgumentException('Could not parse delivery receipt: '.$this->message."\n".bin2hex($this->body));
 		}
-		list($matched, $this->id, $this->sub, $this->dlvrd, $this->submitDate, $this->doneDate, $this->stat, $this->err, $this->text) = $matches;
-		
+		$this->id = $this->getArrayValue($matches, 'id');
+		$this->sub = $this->getArrayValue($matches, 'sub');
+		$this->dlvrd = $this->getArrayValue($matches, 'dlvrd');
+		$this->submitDate = $this->getArrayValue($matches, 'submitDate');
+		$this->doneDate = $this->getArrayValue($matches, 'doneDate');
+		$this->stat = $this->getArrayValue($matches, 'stat');
+		$this->err = $this->getArrayValue($matches, 'err');
+		$this->text = $this->getArrayValue($matches, 'text');
+
 		// Convert dates
 		$dp = str_split($this->submitDate,2);
 		$this->submitDate = gmmktime($dp[3],$dp[4],isset($dp[5]) ? $dp[5] : 0,$dp[1],$dp[2],$dp[0]);
 		$dp = str_split($this->doneDate,2);
 		$this->doneDate = gmmktime($dp[3],$dp[4],isset($dp[5]) ? $dp[5] : 0,$dp[1],$dp[2],$dp[0]);
 	}
+
+	private function getArrayValue($array, $key, $default = null){
+		return isset($array[$key]) ? $array[$key] : $default;
+	}
 }
 
 /**