diff --git a/Models/Calendar.php b/Models/Calendar.php
index 023673f..4fb1171 100644
--- a/Models/Calendar.php
+++ b/Models/Calendar.php
@@ -150,7 +150,7 @@ class Calendar
         $this->events[] = $event;
 
         end($this->events);
-        $key = key($this->events);
+        $key = \key($this->events);
         reset($this->events);
 
         return $key;
diff --git a/Models/Event.php b/Models/Event.php
index 0b5838f..a2fa235 100644
--- a/Models/Event.php
+++ b/Models/Event.php
@@ -186,9 +186,9 @@ class Event
     {
         $this->people[] = $person;
 
-        end($this->people);
-        $key = key($this->people);
-        reset($this->people);
+        \end($this->people);
+        $key = \key($this->people);
+        \reset($this->people);
 
         return $key;
     }