diff --git a/spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/MongoTemplate.java b/spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/MongoTemplate.java
index 8c27f268a..3037fe06b 100644
--- a/spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/MongoTemplate.java
+++ b/spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/MongoTemplate.java
@@ -81,6 +81,7 @@ import org.springframework.data.mongodb.core.convert.DbRefResolver;
 import org.springframework.data.mongodb.core.convert.DefaultDbRefResolver;
 import org.springframework.data.mongodb.core.convert.MappingMongoConverter;
 import org.springframework.data.mongodb.core.convert.MongoConverter;
+import org.springframework.data.mongodb.core.convert.MongoCustomConversions;
 import org.springframework.data.mongodb.core.convert.MongoWriter;
 import org.springframework.data.mongodb.core.convert.QueryMapper;
 import org.springframework.data.mongodb.core.convert.UpdateMapper;
@@ -2308,8 +2309,16 @@ public class MongoTemplate implements MongoOperations, ApplicationContextAware,
 	private static final MongoConverter getDefaultMongoConverter(MongoDbFactory factory) {
 
 		DbRefResolver dbRefResolver = new DefaultDbRefResolver(factory);
-		MappingMongoConverter converter = new MappingMongoConverter(dbRefResolver, new MongoMappingContext());
+		MongoCustomConversions conversions = new MongoCustomConversions(Collections.emptyList());
+
+		MongoMappingContext mappingContext = new MongoMappingContext();
+		mappingContext.setSimpleTypeHolder(conversions.getSimpleTypeHolder());
+		mappingContext.afterPropertiesSet();
+
+		MappingMongoConverter converter = new MappingMongoConverter(dbRefResolver, mappingContext);
+		converter.setCustomConversions(conversions);
 		converter.afterPropertiesSet();
+
 		return converter;
 	}
 
diff --git a/spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/ReactiveMongoTemplate.java b/spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/ReactiveMongoTemplate.java
index 5cf0592c6..280241b1b 100644
--- a/spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/ReactiveMongoTemplate.java
+++ b/spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/ReactiveMongoTemplate.java
@@ -22,7 +22,14 @@ import reactor.core.publisher.Flux;
 import reactor.core.publisher.Mono;
 import reactor.util.function.Tuple2;
 
-import java.util.*;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.Iterator;
+import java.util.List;
+import java.util.Map;
 import java.util.Map.Entry;
 import java.util.Optional;
 import java.util.Set;
@@ -63,6 +70,7 @@ import org.springframework.data.mongodb.core.convert.DbRefResolver;
 import org.springframework.data.mongodb.core.convert.DbRefResolverCallback;
 import org.springframework.data.mongodb.core.convert.MappingMongoConverter;
 import org.springframework.data.mongodb.core.convert.MongoConverter;
+import org.springframework.data.mongodb.core.convert.MongoCustomConversions;
 import org.springframework.data.mongodb.core.convert.MongoWriter;
 import org.springframework.data.mongodb.core.convert.QueryMapper;
 import org.springframework.data.mongodb.core.convert.UpdateMapper;
@@ -1925,8 +1933,16 @@ public class ReactiveMongoTemplate implements ReactiveMongoOperations, Applicati
 
 	private static MappingMongoConverter getDefaultMongoConverter() {
 
-		MappingMongoConverter converter = new MappingMongoConverter(NO_OP_REF_RESOLVER, new MongoMappingContext());
+		MongoCustomConversions conversions = new MongoCustomConversions(Collections.emptyList());
+
+		MongoMappingContext context = new MongoMappingContext();
+		context.setSimpleTypeHolder(conversions.getSimpleTypeHolder());
+		context.afterPropertiesSet();
+
+		MappingMongoConverter converter = new MappingMongoConverter(NO_OP_REF_RESOLVER, context);
+		converter.setCustomConversions(conversions);
 		converter.afterPropertiesSet();
+
 		return converter;
 	}
 
diff --git a/spring-data-mongodb/src/test/java/org/springframework/data/mongodb/core/convert/MappingMongoConverterUnitTests.java b/spring-data-mongodb/src/test/java/org/springframework/data/mongodb/core/convert/MappingMongoConverterUnitTests.java
index c9e110036..490a9800d 100644
--- a/spring-data-mongodb/src/test/java/org/springframework/data/mongodb/core/convert/MappingMongoConverterUnitTests.java
+++ b/spring-data-mongodb/src/test/java/org/springframework/data/mongodb/core/convert/MappingMongoConverterUnitTests.java
@@ -25,7 +25,22 @@ import java.math.BigDecimal;
 import java.math.BigInteger;
 import java.net.URL;
 import java.time.LocalDateTime;
-import java.util.*;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.Date;
+import java.util.EnumMap;
+import java.util.EnumSet;
+import java.util.HashMap;
+import java.util.LinkedHashMap;
+import java.util.List;
+import java.util.Locale;
+import java.util.Map;
+import java.util.Optional;
+import java.util.Set;
+import java.util.SortedMap;
+import java.util.TreeMap;
 
 import org.bson.types.ObjectId;
 import org.hamcrest.Matcher;
@@ -98,13 +113,17 @@ public class MappingMongoConverterUnitTests {
 	@Before
 	public void setUp() {
 
+		MongoCustomConversions conversions = new MongoCustomConversions();
+
 		mappingContext = new MongoMappingContext();
 		mappingContext.setApplicationContext(context);
+		mappingContext.setSimpleTypeHolder(conversions.getSimpleTypeHolder());
 		mappingContext.afterPropertiesSet();
 
 		mappingContext.getPersistentEntity(Address.class);
 
 		converter = new MappingMongoConverter(resolver, mappingContext);
+		converter.setCustomConversions(conversions);
 		converter.afterPropertiesSet();
 	}