diff --git a/spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/convert/MappingMongoConverter.java b/spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/convert/MappingMongoConverter.java
index 47f1f96f5..381858822 100644
--- a/spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/convert/MappingMongoConverter.java
+++ b/spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/convert/MappingMongoConverter.java
@@ -41,12 +41,12 @@ import org.springframework.data.convert.EntityInstantiator;
 import org.springframework.data.convert.TypeMapper;
 import org.springframework.data.mapping.Association;
 import org.springframework.data.mapping.PersistentProperty;
+import org.springframework.data.mapping.MappingException;
 import org.springframework.data.mapping.PersistentPropertyAccessor;
 import org.springframework.data.mapping.PreferredConstructor.Parameter;
 import org.springframework.data.mapping.context.MappingContext;
 import org.springframework.data.mapping.model.ConvertingPropertyAccessor;
 import org.springframework.data.mapping.model.DefaultSpELExpressionEvaluator;
-import org.springframework.data.mapping.MappingException;
 import org.springframework.data.mapping.model.ParameterValueProvider;
 import org.springframework.data.mapping.model.PersistentEntityParameterValueProvider;
 import org.springframework.data.mapping.model.PropertyValueProvider;
@@ -86,6 +86,7 @@ import com.mongodb.DBRef;
 public class MappingMongoConverter extends AbstractMongoConverter implements ApplicationContextAware, ValueResolver {
 
 	private static final String INCOMPATIBLE_TYPES = "Cannot convert %1$s of type %2$s into an instance of %3$s! Implement a custom Converter<%2$s, %3$s> and register it with the CustomConversions. Parent object was: %4$s";
+	private static final String INVALID_TYPE_TO_READ = "Expected to read Document %s into type %s but didn't find a PersistentEntity for the latter!";
 
 	protected static final Logger LOGGER = LoggerFactory.getLogger(MappingMongoConverter.class);
 
@@ -241,6 +242,12 @@ public class MappingMongoConverter extends AbstractMongoConverter implements App
 
 		Document target = bson instanceof BasicDBObject ? new Document((BasicDBObject) bson) : (Document) bson;
 
+		MongoPersistentEntity<?> entity = mappingContext.getPersistentEntity(typeToUse);
+
+		if (entity == null) {
+			throw new MappingException(String.format(INVALID_TYPE_TO_READ, target, typeToUse.getType()));
+		}
+
 		return read((MongoPersistentEntity<S>) mappingContext.getRequiredPersistentEntity(typeToUse), target, path);
 	}
 
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 490a9800d..81cc77a7f 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
@@ -1790,6 +1790,19 @@ public class MappingMongoConverterUnitTests {
 		assertThat(converter.read(ClassWithEnumProperty.class, source).enumSet, is(EnumSet.noneOf(SampleEnum.class)));
 	}
 
+	@Test // DATAMONGO-1757
+	public void failsReadingDocumentIntoSimpleType() {
+
+		org.bson.Document nested = new org.bson.Document("key", "value");
+		org.bson.Document source = new org.bson.Document("map", new org.bson.Document("key", nested));
+
+		exception.expect(MappingException.class);
+		exception.expectMessage(nested.toString());
+		exception.expectMessage(Long.class.getName());
+
+		converter.read(TypeWithMapOfLongValues.class, source);
+	}
+
 	static class GenericType<T> {
 		T content;
 	}
@@ -2140,4 +2153,8 @@ public class MappingMongoConverterUnitTests {
 	static class TypeWithPropertyInNestedField {
 		@Field("nested.sample") String sample;
 	}
+
+	static class TypeWithMapOfLongValues {
+		Map<String, Long> map;
+	}
 }