diff --git a/htdocs/core/class/events.class.php b/htdocs/core/class/events.class.php
index fc0c4533b7d..1b8a9eb3291 100644
--- a/htdocs/core/class/events.class.php
+++ b/htdocs/core/class/events.class.php
@@ -141,7 +141,7 @@ class Events // extends CommonObject
 
 		// Clean parameters
 		$this->description = trim($this->description);
-		if (empty($this->user_agent) && !empty($_SERVER['HTTP_USER_AGENT'])) $this->user_agent = $_SERVER['HTTP_USER_AGENT'];
+		if (empty($this->user_agent)) $this->user_agent = (empty($_SERVER['HTTP_USER_AGENT'])?'':$_SERVER['HTTP_USER_AGENT']);
 
 		// Check parameters
 		if (empty($this->description)) { $this->error = 'ErrorBadValueForParameterCreateEventDesc'; return -1; }
diff --git a/htdocs/core/triggers/interface_20_all_Logevents.class.php b/htdocs/core/triggers/interface_20_all_Logevents.class.php
index dc1ef1ab4a2..e1bcaf85034 100644
--- a/htdocs/core/triggers/interface_20_all_Logevents.class.php
+++ b/htdocs/core/triggers/interface_20_all_Logevents.class.php
@@ -174,7 +174,7 @@ class InterfaceLogevents extends DolibarrTriggers
 		$event->dateevent = $date;
 		$event->label = $text;
 		$event->description = $desc;
-		$event->user_agent = $_SERVER["HTTP_USER_AGENT"];
+		$event->user_agent = (empty($_SERVER["HTTP_USER_AGENT"])?'':$_SERVER["HTTP_USER_AGENT"]);
 
 		$result = $event->create($user);
 		if ($result > 0) {