diff --git a/calendar/classes/external/month_exporter.php b/calendar/classes/external/month_exporter.php
index bb599466c94..b71ccc85a3a 100644
--- a/calendar/classes/external/month_exporter.php
+++ b/calendar/classes/external/month_exporter.php
@@ -162,6 +162,10 @@ class month_exporter extends exporter {
                 // The right arrow defined by the theme.
                 'type' => PARAM_RAW,
             ],
+            'defaulteventcontext' => [
+                'type' => PARAM_INT,
+                'default' => null,
+            ],
         ];
     }
 
@@ -182,7 +186,7 @@ class month_exporter extends exporter {
         $previousperiodlink = new moodle_url($this->url);
         $previousperiodlink->param('time', $previousperiod[0]);
 
-        return [
+        $return = [
             'courseid' => $this->calendar->courseid,
             'filter_selector' => $this->get_course_filter_selector($output),
             'weeks' => $this->get_weeks($output),
@@ -200,6 +204,12 @@ class month_exporter extends exporter {
             'rarrow' => $output->rarrow(),
             'includenavigation' => $this->includenavigation,
         ];
+
+        if ($context = $this->get_default_add_context()) {
+            $return['defaulteventcontext'] = $context->id;
+        }
+
+        return $return;
     }
 
     /**
@@ -211,9 +221,6 @@ class month_exporter extends exporter {
     protected function get_course_filter_selector(renderer_base $output) {
         $content = '';
         $content .= $output->course_filter_selector($this->url, get_string('detailedmonthviewfor', 'calendar'));
-        if (calendar_user_can_add_event($this->calendar->course)) {
-            $content .= $output->add_event_button($this->calendar->courseid, 0, 0, 0, $this->calendar->time);
-        }
 
         return $content;
     }
@@ -361,4 +368,17 @@ class month_exporter extends exporter {
 
         return $this;
     }
+
+    /**
+     * Get the default context for use when adding a new event.
+     *
+     * @return null|\context
+     */
+    protected function get_default_add_context() {
+        if (calendar_user_can_add_event($this->calendar->course)) {
+            return \context_course::instance($this->calendar->course->id);
+        }
+
+        return null;
+    }
 }
diff --git a/calendar/renderer.php b/calendar/renderer.php
index 74b98c6b42b..484265e113b 100644
--- a/calendar/renderer.php
+++ b/calendar/renderer.php
@@ -114,37 +114,20 @@ class core_calendar_renderer extends plugin_renderer_base {
     }
 
     /**
-     * Creates a button to add a new event
+     * Creates a button to add a new event.
      *
      * @param int $courseid
-     * @param int $day
-     * @param int $month
-     * @param int $year
-     * @param int $time the unixtime, used for multiple calendar support. The values $day,
-     *     $month and $year are kept for backwards compatibility.
+     * @param int $unused1
+     * @param int $unused2
+     * @param int $unused3
+     * @param int $unused4
      * @return string
      */
-    public function add_event_button($courseid, $day = null, $month = null, $year = null, $time = null) {
-        // If a day, month and year were passed then convert it to a timestamp. If these were passed
-        // then we can assume the day, month and year are passed as Gregorian, as no where in core
-        // should we be passing these values rather than the time. This is done for BC.
-        if (!empty($day) && !empty($month) && !empty($year)) {
-            if (checkdate($month, $day, $year)) {
-                $time = make_timestamp($year, $month, $day);
-            } else {
-                $time = time();
-            }
-        } else if (empty($time)) {
-            $time = time();
-        }
-
-        $coursecontext = \context_course::instance($courseid);
-        $attributes = [
-            'class' => 'btn btn-secondary pull-xs-right pull-right',
-            'data-context-id' => $coursecontext->id,
-            'data-action' => 'new-event-button'
+    public function add_event_button($courseid, $unused1 = null, $unused2 = null, $unused3 = null, $unused4 = null) {
+        $data = [
+            'contextid' => (\context_course::instance($courseid))->id,
         ];
-        return html_writer::tag('button', get_string('newevent', 'calendar'), $attributes);
+        return $this->render_from_template('core_calendar/add_event_button', $data);
     }
 
     /**
diff --git a/calendar/templates/add_event_button.mustache b/calendar/templates/add_event_button.mustache
new file mode 100644
index 00000000000..654a9d995ac
--- /dev/null
+++ b/calendar/templates/add_event_button.mustache
@@ -0,0 +1,43 @@
+{{!
+    This file is part of Moodle - http://moodle.org/
+
+    Moodle is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    Moodle is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+}}
+{{!
+    @template calendar/add_event_button
+
+    Button to launch the "Add new event" dialogue.
+
+    The purpose of this template is to render the button used to generate the new event dialogue.
+
+    Classes required for JS:
+    * none
+
+    Data attributes required for JS:
+    * none
+
+    Example context (json):
+    {
+        "defaulteventcontext": "2"
+    }
+}}
+{{#defaulteventcontext}}
+<button{{!
+    }} class="btn btn-secondary pull-xs-right pull-right"{{!
+    }} data-context-id="{{defaulteventcontext}}"{{!
+    }} data-action="new-event-button"{{!
+    }}>
+    {{#str}}newevent, core_calendar{{/str}}
+</button>
+{{/defaulteventcontext}}
diff --git a/calendar/templates/month_detailed.mustache b/calendar/templates/month_detailed.mustache
index e6ca7776bdb..baa901345f1 100644
--- a/calendar/templates/month_detailed.mustache
+++ b/calendar/templates/month_detailed.mustache
@@ -31,8 +31,14 @@
     {
     }
 }}
-<div class="calendarwrapper" data-courseid="{{courseid}}" data-month="{{date.mon}}" data-year="{{date.year}}">
+<div{{!
+    }} class="calendarwrapper"{{!
+    }} data-courseid="{{courseid}}"{{!
+    }} data-month="{{date.mon}}"{{!
+    }} data-year="{{date.year}}"{{!
+    }}>
     {{> core_calendar/header }}
+    {{> core_calendar/add_event_button}}
     {{> core_calendar/month_navigation }}
     {{> core/overlay_loading}}
     <table id="month-detailed-{{uniqid}}" class="calendarmonth calendartable card-deck m-b-0">