diff --git a/calendar/classes/external/month_exporter.php b/calendar/classes/external/month_exporter.php
index 2d9e7963f40..617cd40345d 100644
--- a/calendar/classes/external/month_exporter.php
+++ b/calendar/classes/external/month_exporter.php
@@ -246,10 +246,10 @@ class month_exporter extends exporter {
             'date' => (new date_exporter($date))->export($output),
             'periodname' => userdate($this->calendar->time, get_string('strftimemonthyear')),
             'previousperiod' => (new date_exporter($previousperiod))->export($output),
-            'previousperiodname' => $previousperiod['month'],
+            'previousperiodname' => userdate($previousperiod[0], get_string('strftimemonth')),
             'previousperiodlink' => $previousperiodlink->out(false),
             'nextperiod' => (new date_exporter($nextperiod))->export($output),
-            'nextperiodname' => $nextperiod['month'],
+            'nextperiodname' => userdate($nextperiod[0], get_string('strftimemonth')),
             'nextperiodlink' => $nextperiodlink->out(false),
             'larrow' => $output->larrow(),
             'rarrow' => $output->rarrow(),
diff --git a/lang/en/langconfig.php b/lang/en/langconfig.php
index 4d88b365b75..e4d6647c3f1 100644
--- a/lang/en/langconfig.php
+++ b/lang/en/langconfig.php
@@ -50,6 +50,7 @@ $string['strftimedaydate'] = '%A, %d %B %Y';
 $string['strftimedaydatetime'] = '%A, %d %B %Y, %I:%M %p';
 $string['strftimedayshort'] = '%A, %d %B';
 $string['strftimedaytime'] = '%a, %H:%M';
+$string['strftimemonth'] = '%B';
 $string['strftimemonthyear'] = '%B %Y';
 $string['strftimerecent'] = '%d %b, %H:%M';
 $string['strftimerecentfull'] = '%a, %d %b %Y, %I:%M %p';
diff --git a/lib/classes/string_manager_standard.php b/lib/classes/string_manager_standard.php
index e6b79d807a9..fc1c3c44f82 100644
--- a/lib/classes/string_manager_standard.php
+++ b/lib/classes/string_manager_standard.php
@@ -309,6 +309,7 @@ class core_string_manager_standard implements core_string_manager {
             'strftimedaydatetime' => 1,
             'strftimedayshort' => 1,
             'strftimedaytime' => 1,
+            'strftimemonth' => 1,
             'strftimemonthyear' => 1,
             'strftimerecent' => 1,
             'strftimerecentfull' => 1,