diff --git a/apm-sniffer/apm-sdk-plugin/mongodb-3.x-plugin/src/main/java/org/apache/skywalking/apm/plugin/mongodb/v3/MongoDBMethodInterceptor.java b/apm-sniffer/apm-sdk-plugin/mongodb-3.x-plugin/src/main/java/org/apache/skywalking/apm/plugin/mongodb/v3/MongoDBMethodInterceptor.java
index 9987e3d05..5f85d747a 100644
--- a/apm-sniffer/apm-sdk-plugin/mongodb-3.x-plugin/src/main/java/org/apache/skywalking/apm/plugin/mongodb/v3/MongoDBMethodInterceptor.java
+++ b/apm-sniffer/apm-sdk-plugin/mongodb-3.x-plugin/src/main/java/org/apache/skywalking/apm/plugin/mongodb/v3/MongoDBMethodInterceptor.java
@@ -100,7 +100,7 @@ public class MongoDBMethodInterceptor implements InstanceMethodsAroundIntercepto
             BsonDocument filter = ((ListCollectionsOperation)obj).getFilter();
             return limitFilter(filter.toString());
         } else if (obj instanceof MapReduceWithInlineResultsOperation) {
-            BsonDocument filter = ((ListCollectionsOperation)obj).getFilter();
+            BsonDocument filter = ((MapReduceWithInlineResultsOperation)obj).getFilter();
             return limitFilter(filter.toString());
         } else if (obj instanceof DeleteOperation) {
             List<DeleteRequest> writeRequestList = ((DeleteOperation)obj).getDeleteRequests();