Index: prepopulate.module
===================================================================
--- prepopulate.module	(Revision 765)
+++ prepopulate.module	(Arbeitskopie)
@@ -43,8 +43,15 @@
  *   String or array. Value(s) to be applied to the element.
  */
 function _prepopulate_get_walk(&$form, &$getslice) {
-  if (!is_array($getslice)) {
-    $form['#default_value'] = $getslice;
+  if (!is_null($form['#default_value'])) {
+    if (is_array($getslice))
+    {
+      if (!is_array($form['#default_value'])) return; // something went wrong
+      $form['#default_value'] = array_merge($form['#default_value'], $getslice);
+    }
+    else {
+      $form['#default_value'] = $getslice;
+    }
   }
   else {
     foreach (array_keys($getslice) as $getvar) {