diff --git a/htdocs/admin/eventorganization.php b/htdocs/admin/eventorganization.php
index 44bd0b035c6..c7b698ea9eb 100644
--- a/htdocs/admin/eventorganization.php
+++ b/htdocs/admin/eventorganization.php
@@ -264,7 +264,7 @@ if ($action == 'edit') {
 			} elseif (preg_match('/thirdparty_type/', $val['type'])) {
 				require_once DOL_DOCUMENT_ROOT.'/core/class/html.formcompany.class.php';
 				$formcompany = new FormCompany($db);
-				print $formcompany->selectProspectCustomerType($conf->global->{$constname}, $constname);
+				print $formcompany->selectProspectCustomerType($conf->global->{$constname}, $constname, 'customerorprospect', 'form', '', 1);
 			} elseif ($val['type'] == 'securekey') {
 				print '<input required="required" type="text" class="flat" id="'.$constname.'" name="'.$constname.'" value="'.(GETPOST($constname, 'alpha') ?GETPOST($constname, 'alpha') : $conf->global->{$constname}).'" size="40">';
 				if (!empty($conf->use_javascript_ajax)) {
diff --git a/htdocs/core/class/html.formcompany.class.php b/htdocs/core/class/html.formcompany.class.php
index 3e2c3588405..94ab9caf5f9 100644
--- a/htdocs/core/class/html.formcompany.class.php
+++ b/htdocs/core/class/html.formcompany.class.php
@@ -998,16 +998,16 @@ class FormCompany extends Form
 	/**
 	 * Return a HTML select for thirdparty type
 	 *
-	 * @param int $selected selected value
-	 * @param string $htmlname HTML select name
-	 * @param string $htmlidname HTML select id
-	 * @param string $typeinput HTML output
-	 * @param string $morecss More css
-	 * @return string HTML string
+	 * @param int 		$selected 		Selected value
+	 * @param string 	$htmlname 		HTML select name
+	 * @param string 	$htmlidname 	HTML select id
+	 * @param string 	$typeinput 		HTML output
+	 * @param string 	$morecss 		More css
+	 * @param string	$allowempty		Allow empty value or not
+	 * @return string 					HTML string
 	 */
-	public function selectProspectCustomerType($selected, $htmlname = 'client', $htmlidname = 'customerprospect', $typeinput = 'form', $morecss = '')
+	public function selectProspectCustomerType($selected, $htmlname = 'client', $htmlidname = 'customerprospect', $typeinput = 'form', $morecss = '', $allowempty = '')
 	{
-
 		global $conf, $langs;
 		if (!empty($conf->global->SOCIETE_DISABLE_PROSPECTS) && !empty($conf->global->SOCIETE_DISABLE_CUSTOMERS) && empty($conf->fournisseur->enabled)) {
 			return '' ;
@@ -1015,8 +1015,14 @@ class FormCompany extends Form
 
 		$out = '<select class="flat '.$morecss.'" name="'.$htmlname.'" id="'.$htmlidname.'">';
 		if ($typeinput == 'form') {
-			if ($selected == '' || $selected == '-1') {
-				$out .= '<option value="-1">&nbsp;</option>';
+			if ($allowempty || ($selected == '' || $selected == '-1')) {
+				$out .= '<option value="-1">';
+				if (is_numeric($allowempty)) {
+					$out .= '&nbsp;';
+				} else {
+					$out .= $langs->trans($allowempty);
+				}
+				$out .= '</option>';
 			}
 			if (empty($conf->global->SOCIETE_DISABLE_PROSPECTS)) {
 				$out .= '<option value="2"'.($selected == 2 ? ' selected' : '').'>'.$langs->trans('Prospect').'</option>';
diff --git a/htdocs/eventorganization/class/conferenceorboothattendee.class.php b/htdocs/eventorganization/class/conferenceorboothattendee.class.php
index 9185ab5992f..c870f6daafa 100644
--- a/htdocs/eventorganization/class/conferenceorboothattendee.class.php
+++ b/htdocs/eventorganization/class/conferenceorboothattendee.class.php
@@ -197,7 +197,7 @@ class ConferenceOrBoothAttendee extends CommonObject
 		if (!empty($conf->global->EVENTORGANIZATION_FILTERATTENDEES_CAT)) {
 			$this->fields['fk_soc']['type'] .= ' AND rowid IN (SELECT DISTINCT c.fk_soc FROM '.MAIN_DB_PREFIX.'categorie_societe as c WHERE c.fk_categorie='.(int) $conf->global->EVENTORGANIZATION_FILTERATTENDEES_CAT.')';
 		}
-		if ($conf->global->EVENTORGANIZATION_FILTERATTENDEES_TYPE!=='') {
+		if ($conf->global->EVENTORGANIZATION_FILTERATTENDEES_TYPE !== '') {
 			$this->fields['fk_soc']['type'] .= ' AND client='.(int) $conf->global->EVENTORGANIZATION_FILTERATTENDEES_TYPE;
 		}