diff --git a/nodequeue.install b/nodequeue.install
index 464c22e..778143b 100644
--- a/nodequeue.install
+++ b/nodequeue.install
@@ -450,45 +450,57 @@ function nodequeue_update_6005() {
 function nodequeue_update_6006() {
   $ret = array();
 
-  // Delete existing indexes
-  $del_indices = array(
-    'nodequeue_roles' => array('qid', 'rid'),
-    'nodequeue_types' => array('qid', 'type'),
-    'nodequeue_subqueue' => array('qid', 'reference', 'title'),
-    'nodequeue_nodes' => array('sqid', 'qid_nid'),
-  );
-  foreach($del_indices as $table => $indices) {
-    foreach($indices as $k => $index) {
-      db_drop_index($ret, $table, $table . "_" . $index . "_idx");
+  // Get all indices from {nodequeue_nodes}.
+  $result = db_query("SHOW INDEX FROM {nodequeue_nodes}");
+  while ($index = db_fetch_array($result)) {
+    $nn_indices[$index['Key_name']] = $index;
+  }
+
+  // Check if one the indices exists before trying to drop them.
+  if (isset($nn_indices['nodequeue_nodes_sqid_idx'])) {
+    // Delete existing indexes
+    $del_indices = array(
+      'nodequeue_roles' => array('qid', 'rid'),
+      'nodequeue_types' => array('qid', 'type'),
+      'nodequeue_subqueue' => array('qid', 'reference', 'title'),
+      'nodequeue_nodes' => array('sqid', 'qid_nid'),
+    );
+    foreach($del_indices as $table => $indices) {
+      foreach($indices as $k => $index) {
+        db_drop_index($ret, $table, $table . "_" . $index . "_idx");
+      }
     }
+    // Naming convention incorrect for this one
+    db_drop_index($ret, "nodequeue_nodes", "nodequeue_subqueue_nid_idx");
   }
-  // Naming convention incorrect for this one
-  db_drop_index($ret, "nodequeue_nodes", "nodequeue_subqueue_nid_idx");
-
-  // Create new indexes
-  $add_indexes = array(
-     'nodequeue_roles' => array(
-       'qid' => array('qid'),
-       'rid' => array('rid'),
-     ),
-     'nodequeue_types' => array(
-       'qid' => array('qid'),
-       'type' => array('type'),
-     ),
-     'nodequeue_subqueue' => array(
-       'qid' => array('qid'),
-       'reference' => array('reference'),
-       'title' => array('title'),
-     ),
-     'nodequeue_nodes' => array(
-       'sqid' => array('sqid', 'position'),
-       'qid_nid' => array('qid', 'nid'),
-       'nid' => array('nid'),
-     ),
-  );
-  foreach($add_indexes as $table => $indices) {
-    foreach($indices as $name => $columns) {
-      db_add_index($ret, $table, $name, $columns);
+
+  // Check if the new indices weren't already created.
+  if (!isset($nn_indices['sqid'])) {
+    // Create new indexes
+    $add_indexes = array(
+       'nodequeue_roles' => array(
+         'qid' => array('qid'),
+         'rid' => array('rid'),
+       ),
+       'nodequeue_types' => array(
+         'qid' => array('qid'),
+         'type' => array('type'),
+       ),
+       'nodequeue_subqueue' => array(
+         'qid' => array('qid'),
+         'reference' => array('reference'),
+         'title' => array('title'),
+       ),
+       'nodequeue_nodes' => array(
+         'sqid' => array('sqid', 'position'),
+         'qid_nid' => array('qid', 'nid'),
+         'nid' => array('nid'),
+       ),
+    );
+    foreach($add_indexes as $table => $indices) {
+      foreach($indices as $name => $columns) {
+        db_add_index($ret, $table, $name, $columns);
+      }
     }
   }
   return $ret;