diff --git a/htdocs/eventorganization/lib/eventorganization_conferenceorbooth.lib.php b/htdocs/eventorganization/lib/eventorganization_conferenceorbooth.lib.php
index 3951cc25df7..c26a0f8611c 100644
--- a/htdocs/eventorganization/lib/eventorganization_conferenceorbooth.lib.php
+++ b/htdocs/eventorganization/lib/eventorganization_conferenceorbooth.lib.php
@@ -127,6 +127,7 @@ function conferenceorboothProjectPrepareHead($object)
 	$head[$h][2] = 'conferenceorbooth';
 	// Enable caching of conf or booth count attendees
 	$nbAttendees = 0;
+	$nbConferenceOrBooth= 0;
 	require_once DOL_DOCUMENT_ROOT.'/core/lib/memory.lib.php';
 	$cachekey = 'count_conferenceorbooth_project_'.$object->id;
 	$dataretrieved = dol_getcache($cachekey);