diff --git a/program/views.py b/program/views.py
index 7935ad9f8fbfdbc05de3acd73448ad61d7c93d4a..10309aac5cd07daf9d8752b3ce1c8581ec686a26 100644
--- a/program/views.py
+++ b/program/views.py
@@ -531,9 +531,9 @@ class APITimeSlotViewSet(viewsets.ModelViewSet):
         start = datetime.combine(date.today(), time(0, 0))
         end = start + timedelta(days=60)
 
-        if (start := self.request.query_params.get('start')) and (end := self.request.query_params.get('end')):
-            start = datetime.combine(datetime.strptime(start, '%Y-%m-%d').date(), time(0, 0))
-            end = datetime.combine(datetime.strptime(end, '%Y-%m-%d').date(), time(23, 59))
+        if ('start' in self.request.query_params) and ('end' in self.request.query_params):
+            start = datetime.combine(datetime.strptime(self.request.query_params.get('start'), '%Y-%m-%d').date(), time(0, 0))
+            end = datetime.combine(datetime.strptime(self.request.query_params.get('end'), '%Y-%m-%d').date(), time(23, 59))
 
         # Endpoints