diff --git a/src/agenda_culturel/models.py b/src/agenda_culturel/models.py
index 1d90539..f3de32e 100644
--- a/src/agenda_culturel/models.py
+++ b/src/agenda_culturel/models.py
@@ -1592,15 +1592,19 @@ class Event(models.Model):
         else:
             event_structure["modified_date"] = None
 
-        if "start_time" in event_structure:
+        if "start_time" in event_structure and event_structure["start_time"] != "":
             event_structure["start_time"] = time.fromisoformat(
                 event_structure["start_time"]
             )
+        else:
+            event_structure["start_time"] = None
 
-        if "end_time" in event_structure:
+        if "end_time" in event_structure and event_structure["end_time"] != "":
             event_structure["end_time"] = time.fromisoformat(
                 event_structure["end_time"]
             )
+        else:
+            event_structure["end_time"] = None
 
         if "location" not in event_structure or event_structure["location"] is None:
             event_structure["location"] = ""