diff --git a/views/bootstrap4/class.Bootstrap4.php b/views/bootstrap4/class.Bootstrap4.php
index cd9b50caf..d8209cf9a 100644
--- a/views/bootstrap4/class.Bootstrap4.php
+++ b/views/bootstrap4/class.Bootstrap4.php
@@ -1780,7 +1780,7 @@ $(document).ready(function() {
 			if($users) {
 				$allowempty = $attrdef->getMinValues() == 0;
 				$allowmultiple = $attrdef->getMultipleValues();
-				$content .= "<select class=\"chzn-select\"".($allowempty ? " data-allow-clear=\"true\"" : "")."\" name=\"".$fieldname."[".$attrdef->getId()."]".($allowmultiple ? '[]' : '')."\"".($allowmultiple ? " multiple" : "")." data-placeholder=\"".getMLText("select_user")."\">";
+				$content .= "<select class=\"form-control chzn-select\"".($allowempty ? " data-allow-clear=\"true\"" : "")."\" name=\"".$fieldname."[".$attrdef->getId()."]".($allowmultiple ? '[]' : '')."\"".($allowmultiple ? " multiple" : "")." data-placeholder=\"".getMLText("select_user")."\">";
 				if($allowempty)
 					$content .= "<option value=\"\"></option>";
 				foreach($users as $curuser) {
@@ -1800,7 +1800,7 @@ $(document).ready(function() {
 			if($groups) {
 				$allowempty = $attrdef->getMinValues() == 0;
 				$allowmultiple = $attrdef->getMultipleValues();
-				$content .= "<select class=\"chzn-select\"".($allowempty ? " data-allow-clear=\"true\"" : "")."\" name=\"".$fieldname."[".$attrdef->getId()."]".($allowmultiple ? '[]' : '')."\"".($allowmultiple ? " multiple" : "")." data-placeholder=\"".getMLText("select_group")."\">";
+				$content .= "<select class=\"form-control chzn-select\"".($allowempty ? " data-allow-clear=\"true\"" : "")."\" name=\"".$fieldname."[".$attrdef->getId()."]".($allowmultiple ? '[]' : '')."\"".($allowmultiple ? " multiple" : "")." data-placeholder=\"".getMLText("select_group")."\">";
 				if($allowempty)
 					$content .= "<option value=\"\"></option>";
 				foreach($groups as $curgroup) {
@@ -1823,7 +1823,7 @@ $(document).ready(function() {
 				} else {
 					$content .= "\" data-allow-clear=\"true\"";
 				}
-				$content .= "".((!$norequire && $attrdef->getMinValues() > 0) ? ' required' : '')." class=\"chzn-select\" data-placeholder=\"".getMLText("select_value")."\">";
+				$content .= "".((!$norequire && $attrdef->getMinValues() > 0) ? ' required' : '')." class=\"form-control chzn-select\" data-placeholder=\"".getMLText("select_value")."\">";
 				if(!$attrdef->getMultipleValues()) {
 					$content .= "<option value=\"\"></option>";
 				}