fix: compare timedeltas directly
diff --git a/erpnext/support/doctype/service_level/service_level.py b/erpnext/support/doctype/service_level/service_level.py
index f48d927..0b903fb 100644
--- a/erpnext/support/doctype/service_level/service_level.py
+++ b/erpnext/support/doctype/service_level/service_level.py
@@ -65,9 +65,7 @@
 			support_days.append(support_and_resolution.workday)
 			support_and_resolution.idx = week.index(support_and_resolution.workday) + 1
 
-			start_time, end_time = (datetime.strptime(support_and_resolution.start_time, '%H:%M:%S').time(),
-				datetime.strptime(support_and_resolution.end_time, '%H:%M:%S').time())
-			if start_time >= end_time:
+			if support_and_resolution.start_time >= support_and_resolution.end_time:
 				frappe.throw(_("Start Time can't be greater than or equal to End Time \
 					for {0}.".format(support_and_resolution.workday)))