diff --git a/models/measurement.py b/models/measurement.py
index 145b173..55df69e 100644
--- a/models/measurement.py
+++ b/models/measurement.py
@@ -66,8 +66,8 @@ class MeasurementRecordItem(SQLModel):
     station: StationListResponse
 
 class MeasurementRecord(SQLModel):
-    min_value: MeasurementRecordItem
-    max_value: MeasurementRecordItem
+    min_value: MeasurementRecordItem | None
+    max_value: MeasurementRecordItem | None
 
 class RecordResponse(SQLModel):
     inner_temperature_record: MeasurementRecord