Index: sites/all/modules/node_import/supported/cck/content.inc
===================================================================
--- sites/all/modules/node_import/supported/cck/content.inc	(revision 1322)
+++ sites/all/modules/node_import/supported/cck/content.inc	(working copy)
@@ -233,7 +233,7 @@
               $node->$field_name += array('nids' => $nids);
             }
             else {
-              $node->$field_name += array('nid' => reset($nids));
+              $node->$field_name += array('nids' => reset($nids));
             }
             break;