diff --git a/main/admin/calendar.lib.php b/main/admin/calendar.lib.php
index 1e18e741d5..05e15ab323 100644
--- a/main/admin/calendar.lib.php
+++ b/main/admin/calendar.lib.php
@@ -349,7 +349,7 @@ function display_monthcalendar($month, $year) {
 				$bgcolor = $ii<5 ? "class=\"row_odd\"" : "class=\"row_even\"";
 
 				$dayheader = "$curday";
-				if (key_exists($curday,$data)) {
+				if (array_key_exists($curday,$data)) {
 					$dayheader="<a href='".api_get_self()."?".api_get_cidreq()."&amp;view=list&amp;origin=$origin&amp;month=$month&amp;year=$year&amp;day=$curday#$curday'>".$curday."</a>";
 					foreach ($data[$curday] as $key=>$agenda_item) {
 						foreach ($agenda_item as $key=>$value) {
diff --git a/main/calendar/agenda.inc.php b/main/calendar/agenda.inc.php
index dc5d9409ab..4da2337462 100644
--- a/main/calendar/agenda.inc.php
+++ b/main/calendar/agenda.inc.php
@@ -462,7 +462,7 @@ function display_monthcalendar($month, $year, $agenda_items)
                 $bgcolor = $ii < 5 ? 'class="row_odd"' : 'class="row_even"';
                 $dayheader = Display::div($curday, array('class' => 'agenda_day'));
 
-                if (key_exists($curday, $agenda_items)) {
+                if (array_key_exists($curday, $agenda_items)) {
                     $dayheader = Display::div($curday, array('class' => 'agenda_day'));
                     $events_in_day = msort($agenda_items[$curday], 'start_date_tms');
                     foreach ($events_in_day as $value) {
diff --git a/main/dropbox/dropbox_functions.inc.php b/main/dropbox/dropbox_functions.inc.php
index c929942f84..eda5a3e6b3 100644
--- a/main/dropbox/dropbox_functions.inc.php
+++ b/main/dropbox/dropbox_functions.inc.php
@@ -1195,7 +1195,7 @@ function get_total_number_feedback($file_id = '') {
 */
 function check_number_feedback($key, $array) {
 	if (is_array($array)) {
-		if (key_exists($key, $array)) {
+		if (array_key_exists($key, $array)) {
 			return $array[$key];
 		} else {
 			return 0;