diff --git a/src/applications/harbormaster/storage/build/HarbormasterBuildArtifact.php b/src/applications/harbormaster/storage/build/HarbormasterBuildArtifact.php
--- a/src/applications/harbormaster/storage/build/HarbormasterBuildArtifact.php
+++ b/src/applications/harbormaster/storage/build/HarbormasterBuildArtifact.php
@@ -43,6 +43,9 @@
         'key_target' => array(
           'columns' => array('buildTargetPHID', 'artifactType'),
         ),
+        'key_index' => array(
+          'columns' => array('artifactIndex'),
+        ),
       ),
     ) + parent::getConfiguration();
   }