diff --git a/moodle_dl/moodle/mods/calendar.py b/moodle_dl/moodle/mods/calendar.py
index aee4a23..260349e 100644
--- a/moodle_dl/moodle/mods/calendar.py
+++ b/moodle_dl/moodle/mods/calendar.py
@@ -97,7 +97,7 @@ async def real_fetch_mod_entries(
                     }
                 )
             if course_id not in core_contents:
-                core_contents[course_id] = {}
+                core_contents[course_id] = []
             core_contents[course_id].append(
                 {
                     'id': course_events_section_id,
diff --git a/moodle_dl/version.py b/moodle_dl/version.py
index e956a24..a4be3f1 100644
--- a/moodle_dl/version.py
+++ b/moodle_dl/version.py
@@ -1 +1 @@
-__version__ = '2.3.7'
+__version__ = '2.3.8'