diff --git a/src/mibew/client.php b/src/mibew/client.php
index 9451ea65..0d8d3c8d 100644
--- a/src/mibew/client.php
+++ b/src/mibew/client.php
@@ -142,7 +142,9 @@ if( !isset($_GET['token']) || !isset($_GET['thread']) ) {
 		}
 		if($firstmessage) {
 			$postedid = post_message_($thread['threadid'],$kind_user,$firstmessage,$link,$visitor['name']);
-			commit_thread( $thread['threadid'], array('shownmessageid' => intval($postedid)), $link);
+			if ($postedid) {
+				commit_thread( $thread['threadid'], array('shownmessageid' => intval($postedid)), $link);
+			}
 		}
 		notify_operators($thread, $firstmessage, $link);
 		mysql_close($link);
diff --git a/src/mibew/libs/chat.php b/src/mibew/libs/chat.php
index e086c448..2b9a4d83 100644
--- a/src/mibew/libs/chat.php
+++ b/src/mibew/libs/chat.php
@@ -61,6 +61,9 @@ function next_revision($link)
 function post_message_($threadid, $kind, $message, $link, $from = null, $utime = null, $opid = null)
 {
 	global $mysqlprefix;
+	if (!isset($message) || preg_match('/^\s*$/', $message)) {
+		return 0;
+	}
 	$query = sprintf(
 		"insert into ${mysqlprefix}chatmessage (threadid,ikind,tmessage,tname,agentId,dtmcreated) values (%s,%s,'%s',%s,%s,%s)",
 		intval($threadid),
@@ -69,7 +72,6 @@ function post_message_($threadid, $kind, $message, $link, $from = null, $utime =
 		$from ? "'" . mysql_real_escape_string($from, $link) . "'" : "null",
 		$opid ? intval($opid) : "0",
 		$utime ? "FROM_UNIXTIME(" . intval($utime) . ")" : "CURRENT_TIMESTAMP");
-
 	perform_query($query, $link);
 	return mysql_insert_id($link);
 }
diff --git a/src/mibew/thread.php b/src/mibew/thread.php
index d7e55043..3e8460e8 100644
--- a/src/mibew/thread.php
+++ b/src/mibew/thread.php
@@ -75,7 +75,7 @@ if( $act == "refresh" ) {
 
 	$link = connect();
 	$postedid = post_message_($threadid,$kind,$message,$link,$from,null,$isuser ? null : $operator['operatorid'] );
-	if($isuser && $thread["shownmessageid"] == 0) {
+	if($isuser && $postedid && $thread["shownmessageid"] == 0) {
 		commit_thread( $thread['threadid'], array('shownmessageid' => intval($postedid)), $link);
 	}
 	mysql_close($link);