diff --git a/spring-data-mongodb/src/main/java/org/springframework/data/mongodb/repository/support/MongodbDocumentSerializer.java b/spring-data-mongodb/src/main/java/org/springframework/data/mongodb/repository/support/MongodbDocumentSerializer.java
index 210cb355c..3726e30e2 100644
--- a/spring-data-mongodb/src/main/java/org/springframework/data/mongodb/repository/support/MongodbDocumentSerializer.java
+++ b/spring-data-mongodb/src/main/java/org/springframework/data/mongodb/repository/support/MongodbDocumentSerializer.java
@@ -20,7 +20,6 @@ import java.util.Collection;
 import java.util.LinkedHashSet;
 import java.util.List;
 import java.util.Map;
-import java.util.Map.Entry;
 import java.util.regex.Pattern;
 
 import org.bson.BsonJavaScript;
@@ -49,6 +48,7 @@ import com.querydsl.mongodb.MongodbOps;
  * @author laimw
  * @author Mark Paluch
  * @author Christoph Strobl
+ * @author Mikhail Kaduchka
  * @since 2.1
  */
 abstract class MongodbDocumentSerializer implements Visitor<Object, Void> {
@@ -184,8 +184,8 @@ abstract class MongodbDocumentSerializer implements Visitor<Object, Void> {
 			Map<Object, Object> lhs = (Map<Object, Object>) handle(expr.getArg(0));
 			Map<Object, Object> rhs = (Map<Object, Object>) handle(expr.getArg(1));
 
-			LinkedHashSet<Entry<Object, Object>> lhs2 = new LinkedHashSet<>(lhs.entrySet());
-			lhs2.retainAll(rhs.entrySet());
+			LinkedHashSet<Object> lhs2 = new LinkedHashSet<>(lhs.keySet());
+			lhs2.retainAll(rhs.keySet());
 
 			if (lhs2.isEmpty()) {
 				lhs.putAll(rhs);
diff --git a/spring-data-mongodb/src/test/java/org/springframework/data/mongodb/repository/support/SpringDataMongodbSerializerUnitTests.java b/spring-data-mongodb/src/test/java/org/springframework/data/mongodb/repository/support/SpringDataMongodbSerializerUnitTests.java
index b7d6add63..f854682dc 100644
--- a/spring-data-mongodb/src/test/java/org/springframework/data/mongodb/repository/support/SpringDataMongodbSerializerUnitTests.java
+++ b/spring-data-mongodb/src/test/java/org/springframework/data/mongodb/repository/support/SpringDataMongodbSerializerUnitTests.java
@@ -15,17 +15,16 @@
  */
 package org.springframework.data.mongodb.repository.support;
 
+import static com.querydsl.core.types.ExpressionUtils.path;
+import static com.querydsl.core.types.ExpressionUtils.predicate;
+import static com.querydsl.core.types.dsl.Expressions.*;
 import static org.hamcrest.Matchers.*;
 import static org.junit.Assert.*;
-import static org.springframework.data.mongodb.core.DocumentTestUtils.*;
 
-import java.util.ArrayList;
 import java.util.Collections;
-import java.util.List;
 
 import org.bson.Document;
 import org.bson.types.ObjectId;
-import org.hamcrest.collection.IsIterableContainingInOrder;
 import org.junit.Before;
 import org.junit.Test;
 import org.junit.runner.RunWith;
@@ -43,6 +42,8 @@ import org.springframework.data.mongodb.repository.Person.Sex;
 import org.springframework.data.mongodb.repository.QAddress;
 import org.springframework.data.mongodb.repository.QPerson;
 
+import com.querydsl.core.types.Ops;
+import com.querydsl.core.types.PredicateOperation;
 import com.querydsl.core.types.dsl.BooleanExpression;
 import com.querydsl.core.types.dsl.BooleanOperation;
 import com.querydsl.core.types.dsl.PathBuilder;
@@ -55,6 +56,7 @@ import com.querydsl.core.types.dsl.StringPath;
  * @author Oliver Gierke
  * @author Christoph Strobl
  * @author Mark Paluch
+ * @author Mikhail Kaduchka
  */
 @RunWith(MockitoJUnitRunner.class)
 public class SpringDataMongodbSerializerUnitTests {
@@ -163,6 +165,21 @@ public class SpringDataMongodbSerializerUnitTests {
 						+ "\"$ne\" : \"\"}}} , { \"firstname\" : { \"$not\" : { \"$regex\" : \".*\\\\Qfoo\\\\E.*\" , \"$options\" : \"i\"}}}]}"))));
 	}
 
+	@Test // DATAMONGO-2228
+	public void retainsOpsInAndExpression() {
+
+		PredicateOperation testExpression = predicate(Ops.AND,
+				predicate(Ops.OR, predicate(Ops.EQ, path(Object.class, "firstname"), constant("John")),
+						predicate(Ops.EQ, path(Object.class, "firstname"), constant("Sarah"))),
+				predicate(Ops.OR, predicate(Ops.EQ, path(Object.class, "lastname"), constant("Smith")),
+						predicate(Ops.EQ, path(Object.class, "lastname"), constant("Connor"))));
+
+		Document result = (Document) serializer.visit(testExpression, null);
+
+		assertThat(result.toJson(), is(
+				"{\"$and\": [{\"$or\": [{\"firstname\": \"John\"}, {\"firstname\": \"Sarah\"}]}, {\"$or\": [{\"lastname\": \"Smith\"}, {\"lastname\": \"Connor\"}]}]}"));
+	}
+
 	class Address {
 		String id;
 		String street;