diff --git a/flink-connector-mongodb-cdc/src/main/java/com/ververica/cdc/connectors/mongodb/table/MongoDBConnectorDeserializationSchema.java b/flink-connector-mongodb-cdc/src/main/java/com/ververica/cdc/connectors/mongodb/table/MongoDBConnectorDeserializationSchema.java
index db4e937fc8..9d392fb5e6 100644
--- a/flink-connector-mongodb-cdc/src/main/java/com/ververica/cdc/connectors/mongodb/table/MongoDBConnectorDeserializationSchema.java
+++ b/flink-connector-mongodb-cdc/src/main/java/com/ververica/cdc/connectors/mongodb/table/MongoDBConnectorDeserializationSchema.java
@@ -124,10 +124,9 @@ public void deserialize(SourceRecord record, Collector<RowData> out) throws Exce
         Schema valueSchema = record.valueSchema();
 
         OperationType op = operationTypeFor(record);
+
         BsonDocument documentKey =
-                checkNotNull(
-                        extractBsonDocument(
-                                value, valueSchema, MongoDBEnvelope.DOCUMENT_KEY_FIELD));
+                extractBsonDocument(value, valueSchema, MongoDBEnvelope.DOCUMENT_KEY_FIELD);
         BsonDocument fullDocument =
                 extractBsonDocument(value, valueSchema, MongoDBEnvelope.FULL_DOCUMENT_FIELD);