diff --git a/includes/datastream.version.inc b/includes/datastream.version.inc
index b9865f73..6b37335d 100644
--- a/includes/datastream.version.inc
+++ b/includes/datastream.version.inc
@@ -253,10 +253,14 @@ function islandora_datastream_version_replace_form($form, &$form_state, Abstract
   $form_state['dsid'] = $datastream->id;
   $form_state['object'] = $object;
   $extensions = islandora_get_datastreams_requirements_from_models($object->models);
-  $ext = array(NULL);
-  if(isset($extensions[$datastream->id]['mime'])) {
-    $ext = array(implode(",", $extensions[$datastream->id]['mime']));
+  $mime_detect = new MimeDetect();
+  $ext = array();
+  foreach ($extensions[$datastream->id]['mime'] as $key => $value) {
+    $str = $mime_detect->getExtension($value);
+    array_push($ext, $str);
   }
+  $comma = sizeof($ext) > 1 ? "," : "";
+  $ext = array(implode($comma, $ext));
   $upload_size = min((int) ini_get('post_max_size'), (int) ini_get('upload_max_filesize'));
   return array(
     'dsid_fieldset' => array(
@@ -318,7 +322,7 @@ function islandora_datastream_version_replace_form_submit($form, &$form_state) {
   catch (exception $e) {
     drupal_set_message(t('An error occurred during datastream updates. See watchlog for more information.'), 'error');
     watchdog('islandora',
-      'Failed to add new versionable datastream.</br>code: @code<br/>message: @msg',
+      'Failed to add new versionable datastream.<br/>code: @code<br/>message: @msg',
       array(
         '@code' => $e->getCode(),
         '@msg' => $e->getMessage(),
diff --git a/islandora.module b/islandora.module
index 2d92f38d..a149c5a7 100644
--- a/islandora.module
+++ b/islandora.module
@@ -609,8 +609,8 @@ function islandora_permission() {
       'description' => t('Regenerate derivatives for an object or per datastream.'),
     ),
     ISLANDORA_REPLACE_DATASTREAM_CONTENT => array(
-      'title' => t('Replace derivatives'),
-      'description' => t('Replace derivatives for an object or per datastream.'),
+      'title' => t('Replace datastreams'),
+      'description' => t('Replace datastreams for an object or per datastream.'),
     ),
   );
 }
@@ -1893,7 +1893,8 @@ function islandora_islandora_datastream_access($op, AbstractDatastream $datastre
     $hooks = islandora_invoke_hook_list(ISLANDORA_DERVIATIVE_CREATION_HOOK, $object->models, array($object));
     $hooks = islandora_filter_derivatives($hooks, array('force' => TRUE), $object);
     foreach ($hooks as $hook) {
-      if ($hook['destination_dsid'] == $datastream->id && islandora_datastream_access(ISLANDORA_VIEW_OBJECTS, $object[$hook['source_dsid']], $user)) {
+      if ($hook['destination_dsid'] == $datastream->id &&
+        (is_null($hook['source_dsid']) || islandora_datastream_access(ISLANDORA_VIEW_OBJECTS, $object[$hook['source_dsid']], $user))) {
         $applicable_hook = TRUE;
         break;
       }
diff --git a/theme/theme.inc b/theme/theme.inc
index 30bcf9ff..c81a918d 100644
--- a/theme/theme.inc
+++ b/theme/theme.inc
@@ -23,10 +23,9 @@ function islandora_preprocess_islandora_default_edit(array &$variables) {
   $header[] = array('data' => t('Size'));
   if (user_access(ISLANDORA_VIEW_DATASTREAM_HISTORY)) {
     $header[] = array('data' => t('Versions'));
-    $header[] = array('data' => t('Replace'));
   }
 
-  $header[] = array('data' => t('Operations'), 'colspan' => '4');
+  $header[] = array('data' => t('Operations'), 'colspan' => '5');
 
   $table_attributes = array('class' => array('manage-datastreams'));
   $rows = array();