diff -u b/multifield.migrate.inc b/multifield.migrate.inc
--- b/multifield.migrate.inc
+++ b/multifield.migrate.inc
@@ -25,7 +25,6 @@
  * $this->addFieldMapping('field_my_multifield:field_description:format')
  *   ->defaultValue('plain_text');
  * @endcode
- *
  */
 
 /**
@@ -108,7 +107,6 @@
    *
    * Then, each set of multifield values can be migrated in using the
    * appropriate field handlers.
-   *
    */
   public function prepare($entity, array $field_info, array $instance, array $values) {
     // Get the subfield arguments.
@@ -117,12 +115,14 @@
     // Get rid of arguments for subfields if they exist.
     foreach ($arguments as $key => $data) {
       if (is_array($arguments[$key]) && array_key_exists('arguments', $arguments[$key])) {
-        // Save off arguments (e.g. preserve_files, file_function) to another array.
+        // Save off arguments (e.g. preserve_files, file_function) to another
+        // array.
         // If this is not an array then the value of $subfield_arguments
         // gets overridcen on every iteration of the loop.
         $subfield_arguments[$key] = $data['arguments'];
         unset($arguments[$key]['arguments']);
-        // If this is set then only the first value of the multivalued field will get imported.
+        // If this is set then only the first value of the multivalued field
+        // will get imported.
         // $arguments[$key] = $arguments[$key][0];
       }
     }
@@ -173,12 +173,15 @@
       foreach ($subinstances as $subfield_name => $subinstance) {
         if (property_exists($pseudo_entity, $subfield_name)) {
           $subfield = field_info_field($subfield_name);
-          // The fourth value passed should be an array with an 'arguments' key containing $subfield_arguments.
+          // The fourth value passed should be an array with an 'arguments' key
+          // containing $subfield_arguments.
           $values = array();
-          foreach($pseudo_entity->{$subfield_name} as $key => $subfield_data) {
+          foreach ($pseudo_entity->{$subfield_name} as $key => $subfield_data) {
             $values[] = $pseudo_entity->{$subfield_name}[$key];
           }
-          $values['arguments'] = $subfield_arguments[$subfield_name];
+          if (isset($subfield_arguments) && array_key_exists($subfield_name, $subfield_arguments)) {
+            $values['arguments'] = $subfield_arguments[$subfield_name];
+          }
           $pseudo_entity->$subfield_name = migrate_field_handler_invoke_all($pseudo_entity, $subfield, $subinstance, $values);
         }
       }