diff --git node_reference/node_reference.module node_reference/node_reference.module
index fc2dd84..fa6618b 100644
--- node_reference/node_reference.module
+++ node_reference/node_reference.module
@@ -36,11 +36,25 @@ function node_reference_field_info() {
       'default_formatter' => 'node_reference_default',
       // Support hook_entity_property_info() from contrib "Entity API".
       'property_type' => 'node',
+      'property_callbacks' => array('node_reference_field_property_callback'),
     ),
   );
 }
 
 /**
+ * Property callback for node reference fields to correctly specify the content
+ * type of referenced nodes, if only one is allowed. Used by the Entity API
+ * contrib module.
+ */
+function node_reference_field_property_callback(&$info, $entity_type, $field, $instance, $field_type) {
+  if (count($field['settings']['referenceable_types']) == 1) {
+    $property = &$info[$entity_type]['bundles'][$instance['bundle']]['properties'][$field['field_name']];
+    $type = reset($field['settings']['referenceable_types']);
+    $property['bundle'] = $type;
+  }
+}
+
+/**
  * Implements hook_field_schema().
  */
 function node_reference_field_schema($field) {