diff --git a/mappers/field.inc b/mappers/field.inc
index 615b9a5..91eebe8 100644
--- a/mappers/field.inc
+++ b/mappers/field.inc
@@ -16,12 +16,20 @@ function field_feeds_presave(FeedsSource $source, $entity, $item, $entity_id) {
     return;
   }
 
+  // Gather the fields that Feeds is mapping to.
+  $feeds_fields = array();
+  foreach ($source->importer()->processor->getMappings() as $mapping) {
+    list($field) = explode(':', $mapping['target']);
+    $feeds_fields[$field] = TRUE;
+  }
+
   list(, , $bundle) = entity_extract_ids($entity_type, $entity);
 
   foreach (field_info_instances($entity_type, $bundle) as $instance) {
     $field_name = $instance['field_name'];
 
-    if (empty($entity->$field_name)) {
+    // Skip fields that Feeds isn't mapping to, and empty fields.
+    if (!isset($feeds_fields[$field_name]) || empty($entity->$field_name)) {
       continue;
     }