diff --git a/spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/convert/CustomConversions.java b/spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/convert/CustomConversions.java
index 139a40622..01376f3f8 100644
--- a/spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/convert/CustomConversions.java
+++ b/spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/convert/CustomConversions.java
@@ -104,8 +104,10 @@ public class CustomConversions {
 	}
 
 	/**
-	 * Returns whether the given type is considered to be simple.
+	 * Returns whether the given type is considered to be simple. That means it's either a general simple type or we have
+	 * a writing {@link Converter} registered for a particular type.
 	 * 
+	 * @see SimpleTypeHolder#isSimpleType(Class)
 	 * @param type
 	 * @return
 	 */
@@ -176,7 +178,6 @@ public class CustomConversions {
 
 		if (isMongoBasicType(pair.getSourceType())) {
 			readingPairs.add(pair);
-			customSimpleTypes.add(pair.getTargetType());
 		}
 
 		if (isMongoBasicType(pair.getTargetType())) {
diff --git a/spring-data-mongodb/src/test/java/org/springframework/data/mongodb/core/convert/CustomConversionsUnitTests.java b/spring-data-mongodb/src/test/java/org/springframework/data/mongodb/core/convert/CustomConversionsUnitTests.java
index 7c55017af..c521f05e3 100644
--- a/spring-data-mongodb/src/test/java/org/springframework/data/mongodb/core/convert/CustomConversionsUnitTests.java
+++ b/spring-data-mongodb/src/test/java/org/springframework/data/mongodb/core/convert/CustomConversionsUnitTests.java
@@ -50,7 +50,7 @@ public class CustomConversionsUnitTests {
 	@Test
 	public void considersTypesWeRegisteredConvertersForAsSimple() {
 
-		CustomConversions conversions = new CustomConversions(				Arrays.asList(UuidToStringConverter.INSTANCE));
+		CustomConversions conversions = new CustomConversions(Arrays.asList(UuidToStringConverter.INSTANCE));
 		assertThat(conversions.isSimpleType(UUID.class), is(true));
 	}
 
@@ -105,6 +105,15 @@ public class CustomConversionsUnitTests {
 		assertThat(conversionService.canConvert(String.class, UUID.class), is(true));
 	}
 
+	/**
+	 * @see DATADOC-259
+	 */
+	@Test
+	public void doesNotConsiderTypeSimpleIfOnlyReadConverterIsRegistered() {
+		CustomConversions conversions = new CustomConversions(Arrays.asList(StringToUUIDConverter.INSTANCE));
+		assertThat(conversions.isSimpleType(UUID.class), is(false));
+	}
+	
 	enum UuidToStringConverter implements Converter<UUID, String> {
 		INSTANCE;