diff --git a/application/config/constants.php b/application/config/constants.php
index 1d57d408..6e42bd86 100644
--- a/application/config/constants.php
+++ b/application/config/constants.php
@@ -87,5 +87,7 @@ define('CALENDAR_VIEW_TABLE', 'table');
 define('AVAILABILITIES_TYPE_FLEXIBLE', 'flexible');
 define('AVAILABILITIES_TYPE_FIXED', 'fixed');
 
+define('EVENT_MINIMUM_DURATION', 5); // Minutes
+
 /* End of file constants.php */
 /* Location: ./application/config/constants.php */
diff --git a/application/models/Appointments_model.php b/application/models/Appointments_model.php
index bf8d60fe..98f659f2 100644
--- a/application/models/Appointments_model.php
+++ b/application/models/Appointments_model.php
@@ -63,13 +63,12 @@ class Appointments_Model extends CI_Model {
     {
         $this->load->helper('data_validation');
 
-        // If a appointment id is given, check whether the record exists
-        // in the database.
+        // If a appointment id is given, check whether the record exists in the database.
         if (isset($appointment['id']))
         {
-            $num_rows = $this->db->get_where('appointments',
-                ['id' => $appointment['id']])->num_rows();
-            if ($num_rows == 0)
+            $num_rows = $this->db->get_where('appointments', ['id' => $appointment['id']])->num_rows();
+
+            if ($num_rows === 0)
             {
                 throw new Exception('Provided appointment id does not exist in the database.');
             }
@@ -86,6 +85,15 @@ class Appointments_Model extends CI_Model {
             throw new Exception('Appointment end datetime is invalid.');
         }
 
+        // Ensure the appointment lasts longer than the minimum duration (in minutes).
+        $diff = (strtotime($appointment['end_datetime']) - strtotime($appointment['start_datetime'])) / 60;
+
+        if ($diff < EVENT_MINIMUM_DURATION)
+        {
+            throw new Exception('The appointment duration is less than the minimum duration ('
+                . EVENT_MINIMUM_DURATION . ' minutes).');
+        }
+
         // Check if the provider's id is valid.
         $num_rows = $this->db
             ->select('*')